This document provides an overview and table of contents for the book "The Fine Structure of the Nervous System" by Alan Peters, Sanford L. Palay, and Henry deF. Webster. The book contains 10 chapters that describe the fine structure of neurons and their supporting cells in the nervous system at the electron microscopic level. It covers topics such as the neuronal cell body, dendrites, axons, synapses, myelin sheaths, neuroglial cells, ependyma, choroid plexus, and blood vessels. The preface expresses the authors' goal to present an updated account of mammalian neurons and neuroglial cells through extensively revised text and new electron micrographs.
In 1958, Meselsohn and Stahl conducted an experiment showing that DNA replication is semi-conservative. They grew bacteria in a medium containing the heavy isotope nitrogen-15 (N15) and then replicated the bacteria's DNA either once or twice in the light isotope nitrogen-14 (N14). The results showed that after one replication, the parental N15 and new N14 strands remained together, supporting the semi-conservative model of DNA replication.
This document is a biology project on DNA prepared by a student for their class. It includes a certificate authenticating the project, acknowledgements, and a detailed report on the structure and processes of DNA. The report discusses the history of DNA research from its discovery to the modern understanding of its double helix structure. It also explains DNA replication, where two identical DNA molecules are produced, and transcription, where DNA is copied into messenger RNA.
A presentation by Thatayaone Ezekiel Dinama, Kago Relaeng and Michael Moseneke made to the Cardiff Sixth Form College A-Level BioMedical Society on the amazing discovery of the G-Quadruple structure of DNA. The discovery has many unfathomable potential benefits as far as health is concerned. Being interested in studying Medicine (Clinical or Academic) I found it a really intriguing research topic of recent times.
The document summarizes the history of molecular genetics and DNA structure. It describes early discoveries like Friedrich Miescher extracting nuclein from cells in 1869, Gregor Mendel's work on inheritance in the 1800s, and Thomas Hunt Morgan's work with fruit flies in the early 1900s. It then covers later discoveries such as Frederick Griffith's work on bacterial transformation in 1928, Avery, McCarty and MacLeod's experiments in the 1940s showing DNA is the transforming principle, and Hershey and Chase's 1952 experiment proving DNA carries genetic information. It concludes with Watson and Crick determining the double helix structure of DNA using data from Franklin, Wilkins and Chargaff in 1953.
The race to unlock one of the great mysteries of life, the structure of DNA.
Register to explore the whole course here: https://school.bighistoryproject.com/bhplive?WT.mc_id=Slideshare12202017
DNA is made up of nucleotides that contain a sugar, phosphate, and one of four nitrogenous bases (adenine, thymine, guanine, cytosine). The nucleotides are connected in a double helix shape by hydrogen bonds between the bases, with adenine bonding only to thymine and guanine bonding only to cytosine. Studying DNA is important for disease diagnosis and treatment, determining paternity, forensics, and agricultural applications.
DNA contains the genetic instructions that determine traits like appearance and personality. It has a double helix structure with sugars and phosphates forming the sides and nitrogen bases forming the rungs. In the 1950s, Rosalind Franklin discovered the X-ray crystallography structure of DNA. Her work was shared with Watson and Crick, who then constructed a model of DNA's double helix structure, winning a Nobel Prize. DNA replication is the process by which DNA copies itself for cell division, involving enzymes breaking bonds and RNA assisting new strands to form based on base pairing.
Scientists discovered that DNA stores and transmits genetic information between generations of organisms. DNA has a double helix structure with two strands wound around each other. The strands are made up of nucleotides that bond together through specific base pairing between adenine and thymine or guanine and cytosine. Viruses can introduce foreign DNA into bacteria through transformation, changing the bacteria.
In 1958, Meselsohn and Stahl conducted an experiment showing that DNA replication is semi-conservative. They grew bacteria in a medium containing the heavy isotope nitrogen-15 (N15) and then replicated the bacteria's DNA either once or twice in the light isotope nitrogen-14 (N14). The results showed that after one replication, the parental N15 and new N14 strands remained together, supporting the semi-conservative model of DNA replication.
This document is a biology project on DNA prepared by a student for their class. It includes a certificate authenticating the project, acknowledgements, and a detailed report on the structure and processes of DNA. The report discusses the history of DNA research from its discovery to the modern understanding of its double helix structure. It also explains DNA replication, where two identical DNA molecules are produced, and transcription, where DNA is copied into messenger RNA.
A presentation by Thatayaone Ezekiel Dinama, Kago Relaeng and Michael Moseneke made to the Cardiff Sixth Form College A-Level BioMedical Society on the amazing discovery of the G-Quadruple structure of DNA. The discovery has many unfathomable potential benefits as far as health is concerned. Being interested in studying Medicine (Clinical or Academic) I found it a really intriguing research topic of recent times.
The document summarizes the history of molecular genetics and DNA structure. It describes early discoveries like Friedrich Miescher extracting nuclein from cells in 1869, Gregor Mendel's work on inheritance in the 1800s, and Thomas Hunt Morgan's work with fruit flies in the early 1900s. It then covers later discoveries such as Frederick Griffith's work on bacterial transformation in 1928, Avery, McCarty and MacLeod's experiments in the 1940s showing DNA is the transforming principle, and Hershey and Chase's 1952 experiment proving DNA carries genetic information. It concludes with Watson and Crick determining the double helix structure of DNA using data from Franklin, Wilkins and Chargaff in 1953.
The race to unlock one of the great mysteries of life, the structure of DNA.
Register to explore the whole course here: https://school.bighistoryproject.com/bhplive?WT.mc_id=Slideshare12202017
DNA is made up of nucleotides that contain a sugar, phosphate, and one of four nitrogenous bases (adenine, thymine, guanine, cytosine). The nucleotides are connected in a double helix shape by hydrogen bonds between the bases, with adenine bonding only to thymine and guanine bonding only to cytosine. Studying DNA is important for disease diagnosis and treatment, determining paternity, forensics, and agricultural applications.
DNA contains the genetic instructions that determine traits like appearance and personality. It has a double helix structure with sugars and phosphates forming the sides and nitrogen bases forming the rungs. In the 1950s, Rosalind Franklin discovered the X-ray crystallography structure of DNA. Her work was shared with Watson and Crick, who then constructed a model of DNA's double helix structure, winning a Nobel Prize. DNA replication is the process by which DNA copies itself for cell division, involving enzymes breaking bonds and RNA assisting new strands to form based on base pairing.
Scientists discovered that DNA stores and transmits genetic information between generations of organisms. DNA has a double helix structure with two strands wound around each other. The strands are made up of nucleotides that bond together through specific base pairing between adenine and thymine or guanine and cytosine. Viruses can introduce foreign DNA into bacteria through transformation, changing the bacteria.
Cell Culture Techniques (Michael Aschner, Lucio Costa) (Z-Library).pdfsymbssglmr
This document provides prefaces and contributor information for the book "Cell Culture Techniques, Second Edition". The prefaces discuss the Neuromethods series focusing on tools and techniques for investigating the nervous system. The book aims to provide technical protocols as well as theoretical background to help readers understand the origins and potential developments of the techniques. The contributors section lists researchers who contributed chapters applying specific neuroscience methods and models.
Atlas of Regional ANATOMY of the Brain Using MRI nataliej4
This document provides an introduction and overview of the book "Atlas of Regional Anatomy of the Brain Using MRI" by authors J.C. Tamraz and Y.G. Comair. The foreword discusses how MRI has allowed for non-invasive study of brain anatomy and its correlation with function. The preface outlines how MRI revived interest in studying brain morphology and function together by making detailed images of brain structures available. The book aims to facilitate studying brain anatomy through a methodological analysis of functionally oriented morphology using MRI. It focuses on surface anatomy of the brain and examines primary motor cortex, speech, limbic system, and vision through sectioning, 3D rendering, and innovative oblique sections.
Review and development of techniques for studying cellular biophysics with hi...Michael Butler
This thesis investigates techniques for studying cellular biophysics with high frequency ultrasound. It reviews theories of acoustic wave interactions at the molecular level and cellular scale. Experimental work develops thin film aluminum nitride and lithium niobate crystal transducers for generating broadband ultrasound up to 140 MHz. Preliminary testing of these transducers is presented along with the design of a broadband acoustic spectrometry system to study the effects of high frequency sound on actin polymerization in vitro.
The document discusses several key topics in anatomy and physiology:
1) It defines homeostasis as the maintenance of stable internal conditions in the body. Organs like the lungs, kidneys, and GI system help maintain homeostasis.
2) It describes the autonomic nervous system which controls involuntary functions like heart rate and digestion unconsciously.
3) It explains neuron anatomy and how they transmit electrochemical signals through the body via electrical impulses along axons.
This document summarizes recent research on action potential initiation and propagation in neurons. It discusses how direct recordings from axons have provided new insights beyond what is known from somatic recordings alone. Specifically, it finds that axons contain distinct collections of ion channels compared to somatodendritic compartments. This allows axons to exhibit more computational power in determining spike threshold and waveform than traditionally thought. The document reviews sodium channel subtypes, localization, development, and roles in shaping firing properties and ensuring reliable propagation.
This document provides background information on a book titled "Coherent Behavior in Neuronal Networks". It begins with a preface written by the book's four editors - Kresimir Josic, Jonathan Rubin, Manuel A. Matias, and Ranulfo Romo. The preface describes the motivation and goals for the book, which is to provide a sampling of recent research on coherent neuronal network behavior from an interdisciplinary perspective, with contributions from both experimentalists and theorists. It then provides a brief overview of the book's scientific content, which covers topics such as ongoing cortical activity, small neuronal network interactions, spatiotemporal neuronal activity patterns, and coherence in encoding and decoding across different systems.
A history of optogenetics the development of tools for controlling brain circ...merzak emerzak
Optogenetics allows specific control of neural activity with light by expressing light-sensitive microbial opsins in neurons. The development of optogenetics involved adapting opsins like channelrhodopsin and halorhodopsin that transport ions in response to light. Channelrhodopsin was identified as enabling fast activation of neurons with light, and was expressed in neurons to control their activity, demonstrating the potential of optogenetics to causally study neural circuits.
Answer the following questions from the Article belowExercise #1..pdfarjunstores123
Answer the following questions from the Article below:
Exercise #1. Read the following article and then answer the following questions in paragraph
form.
1. How has DNA changed the study of biology over the past 50 years? Explain whether scientists
have shifted to a molecular level in the various subdisciplines of biology. Also, do you believe
any trend to the molecular level will continue far into the future?
2. Explain the role of DNA in the development of an organisms. Does DNA fully provide a
blueprint to create an individual? Can DNA by itself propagate itself or does it require other
molecular machines?
3. In modern biology, which is the role of physics in the study of organisms and their molecules?
Has physics moved to the forefront or does it play an ancillary role? As described in the article,
why are the molecular forces of very low energy in an organism?
Historians have the luxury of look- ing back at human endeavor over long periods of time, but
most scien- tists are too busy working in the present and thinking anxiously about the future and
have no time to view their work in the context of what has gone before. I once remarked that all
graduate students in biology divide history into two epochs: the past 2 years and every- thing else
before that, where Archimedes, Newton, Darwin, Mendel—even Watson and Crick—inhabit a
time-compressed universe as uneasy contemporaries. It seems remark- able that historians once
thought that science progressed by the steady addition of knowl- edge, building the edifice of
scientific truth, brick by brick. In his 1962 book The Struc- ture of Scientific Revolutions,
Thomas Kuhn argued that progress occurs in revolutionary steps by the introduction of new
paradigms, which may be new theories—new ways of looking at the world—or new technical
meth- ods that enhance observation and analysis.
Between Kuhn’s revolutions, scientif ic knowledge does advance by accretion, as there is much
to do to consolidate the new sci- ence. But then, inevitably, unsolved problems accumulate and,
in many cases, the inconsis- tencies have been put to one side and every- body hopes that they
will quietly go away. The edifice becomes rickety; some of its founda- tions are insecure and
many of the bricks have not been well-baked. This is when a new rev- olutionary wave in the
form of new ideas or new techniques appears, which allows us to condemn and demolish the
unsafe or corrupt parts of the edifice and rebuild truth. Often there is great resistance to the new
wave, but as Max Planck pointed out, it succeeds because the opponents grow old and die. The
process is then repeated: The radicals become liberals, the liberals become conservatives, the
conservatives become reactionaries, and the reactionaries disappear. Students of evolu- tion will
recognize this process in the theory of punctuated equilibrium: Organisms stay much the same
for very long periods of time; this is interrupted by bursts of change when novelty appears,
f.
Capítulo de la edición 25 aniversario de "Fundations of the Neuron Doctrine", la clásica obra sobre la 'Doctrina Neuronal" del Profesor en Neurociencia de la Universidad de Yale: Gordon Shepherd.
This document provides a retrospective by Eric Kandel on advances in neuroscience over the past 40 years. It summarizes four periods of growth in understanding memory biology. Early work identified the hippocampus and medial temporal lobe as critical for declarative memory and showed multiple brain systems are involved in procedural memory. Studies of simple reflexes in invertebrates revealed cellular mechanisms of short and long-term memory involving synaptic plasticity. Later, long-term potentiation in the hippocampus was linked to spatial memory, and molecular approaches identified common mechanisms of short-term memory across species.
This thesis investigates how the structural stability of an RNA template strand affects the rate of nonenzymatic template-directed primer extension in the RNA world hypothesis. The author designs RNA template sequences and correlates their predicted structural stability to experimental rates of primer extension. The results show that more structurally stable template sequences have lower rates of extension. This poses a problem for the RNA world, as stable sequences could not replicate. However, the author proposes that some sequences could be "asymmetric", where one strand is unstable and acts as a good template, while its complement is stable and could function as a ribozyme. This solves the replication problem by allowing both unstable templates and stable ribozymes to exist.
Fundamentals of Human Neuropsychology 7th Edition Kolb Test BankPerkinser
Full download : http://alibabadownload.com/product/fundamentals-of-human-neuropsychology-7th-edition-kolb-test-bank/ Fundamentals of Human Neuropsychology 7th Edition Kolb Test Bank
This document provides an overview of a 12-lesson module on growth and development. The lessons will cover topics like growing and changing, growth patterns, cell reproduction, genetics, specialized cells, and proteins. Key concepts include DNA, genes, inheritance, cell division, and how cells become specialized.
Histology is the study of tissues at a microscopic level. In the late 1700s, Bichat described 21 tissues based on gross dissection without a microscope. Improvements to the microscope by Leeuwenhoek allowed other scientists to examine tissues at a microscopic level. In the 17th century, Hooke discovered cells by examining cork with a microscope. Similar compartments were later found in animal tissues. In 1832, Schleiden and Schwann proposed the cell theory that all tissues are composed of cells. Stains were later introduced to increase contrast when examining cells. The basic tissues are epithelial, connective, muscle and nervous tissue. Henle is credited with creating the first histology based on detailed microscopic examination
Discussion Conjoined Twins and Split Brain Patients.docxstirlingvwriters
Split brain patients have had surgery to cut the corpus callosum, revealing two separate minds mediated by different brain hemispheres. One hemisphere can speak while the other can only communicate through gestures. Conjoined twins can have either separate or shared brains/brain regions. Studies of split brain patients and conjoined twins provide insights into brain organization and the concept of personhood.
This document discusses research into growing neurons on silicone as a way to repair damaged neurons and restore cognitive functions. Neurons can grow on silicone due to its similar properties to carbon and ability to transmit electrical signals. Researchers have shown neurons on silicone can control current flow. The hippocampus is an area often damaged in neurological diseases. It plays a key role in memory and spatial awareness. Damage there can cause cognitive deficits treatable by a computer chip that interfaces with brain tissue to perform damaged functions. The goal is to develop this technology to treat conditions like Alzheimer's and epilepsy.
Robert Hooke discovered cells in 1665 using an early microscope. He observed the structures of cork cells. The development of electron microscopes in the 1930s allowed scientists to view cells and organelles at much higher magnifications. Key discoveries included the nucleus by Brown in 1831, living cells by Van Leeuwenhoek in 1674, and the proposal of the cell theory by Schleiden, Schwann, and Virchow from 1838-1858 stating that cells are the fundamental unit of life. Plant cells have additional structures like a cell wall and chloroplasts. The main components of plant cells are the cell membrane, cytoplasm, and nucleus. The nucleus contains DNA and controls the cell.
This document provides an autobiographical introduction to the author's lifelong interest in memory from his childhood experiences in Vienna in 1938 up until receiving the Nobel Prize in Physiology or Medicine in 2000 for his contributions to the study of memory storage in the brain. It describes the author's vivid childhood memories of his 9th birthday and the events of Kristallnacht a few days later when his family was forced to leave their home. This traumatic experience sparked his early interest in understanding human behavior and memory, which first manifested as a focus on history and psychoanalysis in college, before turning to the biological study of the brain and memory in a scientific career spanning over 50 years.
IOSR Journal of Pharmacy (IOSRPHR), www.iosrphr.org, call for paper, research...iosrphr_editor
During a routine dissection of a male cadaver, an anatomical variation was observed in the formation of the right median nerve. The median nerve was formed by four roots, with three roots originating from the lateral cord of the brachial plexus and one root from the medial cord. The four roots joined individually with the medial root to form the median nerve trunk in front of the third part of the axillary artery. However, the further distribution and arterial pattern in the arm was normal. This report discusses the rare occurrence of a median nerve formed by more than two roots and the potential clinical implications of such variations.
Cell Culture Techniques (Michael Aschner, Lucio Costa) (Z-Library).pdfsymbssglmr
This document provides prefaces and contributor information for the book "Cell Culture Techniques, Second Edition". The prefaces discuss the Neuromethods series focusing on tools and techniques for investigating the nervous system. The book aims to provide technical protocols as well as theoretical background to help readers understand the origins and potential developments of the techniques. The contributors section lists researchers who contributed chapters applying specific neuroscience methods and models.
Atlas of Regional ANATOMY of the Brain Using MRI nataliej4
This document provides an introduction and overview of the book "Atlas of Regional Anatomy of the Brain Using MRI" by authors J.C. Tamraz and Y.G. Comair. The foreword discusses how MRI has allowed for non-invasive study of brain anatomy and its correlation with function. The preface outlines how MRI revived interest in studying brain morphology and function together by making detailed images of brain structures available. The book aims to facilitate studying brain anatomy through a methodological analysis of functionally oriented morphology using MRI. It focuses on surface anatomy of the brain and examines primary motor cortex, speech, limbic system, and vision through sectioning, 3D rendering, and innovative oblique sections.
Review and development of techniques for studying cellular biophysics with hi...Michael Butler
This thesis investigates techniques for studying cellular biophysics with high frequency ultrasound. It reviews theories of acoustic wave interactions at the molecular level and cellular scale. Experimental work develops thin film aluminum nitride and lithium niobate crystal transducers for generating broadband ultrasound up to 140 MHz. Preliminary testing of these transducers is presented along with the design of a broadband acoustic spectrometry system to study the effects of high frequency sound on actin polymerization in vitro.
The document discusses several key topics in anatomy and physiology:
1) It defines homeostasis as the maintenance of stable internal conditions in the body. Organs like the lungs, kidneys, and GI system help maintain homeostasis.
2) It describes the autonomic nervous system which controls involuntary functions like heart rate and digestion unconsciously.
3) It explains neuron anatomy and how they transmit electrochemical signals through the body via electrical impulses along axons.
This document summarizes recent research on action potential initiation and propagation in neurons. It discusses how direct recordings from axons have provided new insights beyond what is known from somatic recordings alone. Specifically, it finds that axons contain distinct collections of ion channels compared to somatodendritic compartments. This allows axons to exhibit more computational power in determining spike threshold and waveform than traditionally thought. The document reviews sodium channel subtypes, localization, development, and roles in shaping firing properties and ensuring reliable propagation.
This document provides background information on a book titled "Coherent Behavior in Neuronal Networks". It begins with a preface written by the book's four editors - Kresimir Josic, Jonathan Rubin, Manuel A. Matias, and Ranulfo Romo. The preface describes the motivation and goals for the book, which is to provide a sampling of recent research on coherent neuronal network behavior from an interdisciplinary perspective, with contributions from both experimentalists and theorists. It then provides a brief overview of the book's scientific content, which covers topics such as ongoing cortical activity, small neuronal network interactions, spatiotemporal neuronal activity patterns, and coherence in encoding and decoding across different systems.
A history of optogenetics the development of tools for controlling brain circ...merzak emerzak
Optogenetics allows specific control of neural activity with light by expressing light-sensitive microbial opsins in neurons. The development of optogenetics involved adapting opsins like channelrhodopsin and halorhodopsin that transport ions in response to light. Channelrhodopsin was identified as enabling fast activation of neurons with light, and was expressed in neurons to control their activity, demonstrating the potential of optogenetics to causally study neural circuits.
Answer the following questions from the Article belowExercise #1..pdfarjunstores123
Answer the following questions from the Article below:
Exercise #1. Read the following article and then answer the following questions in paragraph
form.
1. How has DNA changed the study of biology over the past 50 years? Explain whether scientists
have shifted to a molecular level in the various subdisciplines of biology. Also, do you believe
any trend to the molecular level will continue far into the future?
2. Explain the role of DNA in the development of an organisms. Does DNA fully provide a
blueprint to create an individual? Can DNA by itself propagate itself or does it require other
molecular machines?
3. In modern biology, which is the role of physics in the study of organisms and their molecules?
Has physics moved to the forefront or does it play an ancillary role? As described in the article,
why are the molecular forces of very low energy in an organism?
Historians have the luxury of look- ing back at human endeavor over long periods of time, but
most scien- tists are too busy working in the present and thinking anxiously about the future and
have no time to view their work in the context of what has gone before. I once remarked that all
graduate students in biology divide history into two epochs: the past 2 years and every- thing else
before that, where Archimedes, Newton, Darwin, Mendel—even Watson and Crick—inhabit a
time-compressed universe as uneasy contemporaries. It seems remark- able that historians once
thought that science progressed by the steady addition of knowl- edge, building the edifice of
scientific truth, brick by brick. In his 1962 book The Struc- ture of Scientific Revolutions,
Thomas Kuhn argued that progress occurs in revolutionary steps by the introduction of new
paradigms, which may be new theories—new ways of looking at the world—or new technical
meth- ods that enhance observation and analysis.
Between Kuhn’s revolutions, scientif ic knowledge does advance by accretion, as there is much
to do to consolidate the new sci- ence. But then, inevitably, unsolved problems accumulate and,
in many cases, the inconsis- tencies have been put to one side and every- body hopes that they
will quietly go away. The edifice becomes rickety; some of its founda- tions are insecure and
many of the bricks have not been well-baked. This is when a new rev- olutionary wave in the
form of new ideas or new techniques appears, which allows us to condemn and demolish the
unsafe or corrupt parts of the edifice and rebuild truth. Often there is great resistance to the new
wave, but as Max Planck pointed out, it succeeds because the opponents grow old and die. The
process is then repeated: The radicals become liberals, the liberals become conservatives, the
conservatives become reactionaries, and the reactionaries disappear. Students of evolu- tion will
recognize this process in the theory of punctuated equilibrium: Organisms stay much the same
for very long periods of time; this is interrupted by bursts of change when novelty appears,
f.
Capítulo de la edición 25 aniversario de "Fundations of the Neuron Doctrine", la clásica obra sobre la 'Doctrina Neuronal" del Profesor en Neurociencia de la Universidad de Yale: Gordon Shepherd.
This document provides a retrospective by Eric Kandel on advances in neuroscience over the past 40 years. It summarizes four periods of growth in understanding memory biology. Early work identified the hippocampus and medial temporal lobe as critical for declarative memory and showed multiple brain systems are involved in procedural memory. Studies of simple reflexes in invertebrates revealed cellular mechanisms of short and long-term memory involving synaptic plasticity. Later, long-term potentiation in the hippocampus was linked to spatial memory, and molecular approaches identified common mechanisms of short-term memory across species.
This thesis investigates how the structural stability of an RNA template strand affects the rate of nonenzymatic template-directed primer extension in the RNA world hypothesis. The author designs RNA template sequences and correlates their predicted structural stability to experimental rates of primer extension. The results show that more structurally stable template sequences have lower rates of extension. This poses a problem for the RNA world, as stable sequences could not replicate. However, the author proposes that some sequences could be "asymmetric", where one strand is unstable and acts as a good template, while its complement is stable and could function as a ribozyme. This solves the replication problem by allowing both unstable templates and stable ribozymes to exist.
Fundamentals of Human Neuropsychology 7th Edition Kolb Test BankPerkinser
Full download : http://alibabadownload.com/product/fundamentals-of-human-neuropsychology-7th-edition-kolb-test-bank/ Fundamentals of Human Neuropsychology 7th Edition Kolb Test Bank
This document provides an overview of a 12-lesson module on growth and development. The lessons will cover topics like growing and changing, growth patterns, cell reproduction, genetics, specialized cells, and proteins. Key concepts include DNA, genes, inheritance, cell division, and how cells become specialized.
Histology is the study of tissues at a microscopic level. In the late 1700s, Bichat described 21 tissues based on gross dissection without a microscope. Improvements to the microscope by Leeuwenhoek allowed other scientists to examine tissues at a microscopic level. In the 17th century, Hooke discovered cells by examining cork with a microscope. Similar compartments were later found in animal tissues. In 1832, Schleiden and Schwann proposed the cell theory that all tissues are composed of cells. Stains were later introduced to increase contrast when examining cells. The basic tissues are epithelial, connective, muscle and nervous tissue. Henle is credited with creating the first histology based on detailed microscopic examination
Discussion Conjoined Twins and Split Brain Patients.docxstirlingvwriters
Split brain patients have had surgery to cut the corpus callosum, revealing two separate minds mediated by different brain hemispheres. One hemisphere can speak while the other can only communicate through gestures. Conjoined twins can have either separate or shared brains/brain regions. Studies of split brain patients and conjoined twins provide insights into brain organization and the concept of personhood.
This document discusses research into growing neurons on silicone as a way to repair damaged neurons and restore cognitive functions. Neurons can grow on silicone due to its similar properties to carbon and ability to transmit electrical signals. Researchers have shown neurons on silicone can control current flow. The hippocampus is an area often damaged in neurological diseases. It plays a key role in memory and spatial awareness. Damage there can cause cognitive deficits treatable by a computer chip that interfaces with brain tissue to perform damaged functions. The goal is to develop this technology to treat conditions like Alzheimer's and epilepsy.
Robert Hooke discovered cells in 1665 using an early microscope. He observed the structures of cork cells. The development of electron microscopes in the 1930s allowed scientists to view cells and organelles at much higher magnifications. Key discoveries included the nucleus by Brown in 1831, living cells by Van Leeuwenhoek in 1674, and the proposal of the cell theory by Schleiden, Schwann, and Virchow from 1838-1858 stating that cells are the fundamental unit of life. Plant cells have additional structures like a cell wall and chloroplasts. The main components of plant cells are the cell membrane, cytoplasm, and nucleus. The nucleus contains DNA and controls the cell.
This document provides an autobiographical introduction to the author's lifelong interest in memory from his childhood experiences in Vienna in 1938 up until receiving the Nobel Prize in Physiology or Medicine in 2000 for his contributions to the study of memory storage in the brain. It describes the author's vivid childhood memories of his 9th birthday and the events of Kristallnacht a few days later when his family was forced to leave their home. This traumatic experience sparked his early interest in understanding human behavior and memory, which first manifested as a focus on history and psychoanalysis in college, before turning to the biological study of the brain and memory in a scientific career spanning over 50 years.
IOSR Journal of Pharmacy (IOSRPHR), www.iosrphr.org, call for paper, research...iosrphr_editor
During a routine dissection of a male cadaver, an anatomical variation was observed in the formation of the right median nerve. The median nerve was formed by four roots, with three roots originating from the lateral cord of the brachial plexus and one root from the medial cord. The four roots joined individually with the medial root to form the median nerve trunk in front of the third part of the axillary artery. However, the further distribution and arterial pattern in the arm was normal. This report discusses the rare occurrence of a median nerve formed by more than two roots and the potential clinical implications of such variations.
Similar to 1991 peters, palay, webster. the fine structure of the nervous system (20)
Chapter wise All Notes of First year Basic Civil Engineering.pptxDenish Jangid
Chapter wise All Notes of First year Basic Civil Engineering
Syllabus
Chapter-1
Introduction to objective, scope and outcome the subject
Chapter 2
Introduction: Scope and Specialization of Civil Engineering, Role of civil Engineer in Society, Impact of infrastructural development on economy of country.
Chapter 3
Surveying: Object Principles & Types of Surveying; Site Plans, Plans & Maps; Scales & Unit of different Measurements.
Linear Measurements: Instruments used. Linear Measurement by Tape, Ranging out Survey Lines and overcoming Obstructions; Measurements on sloping ground; Tape corrections, conventional symbols. Angular Measurements: Instruments used; Introduction to Compass Surveying, Bearings and Longitude & Latitude of a Line, Introduction to total station.
Levelling: Instrument used Object of levelling, Methods of levelling in brief, and Contour maps.
Chapter 4
Buildings: Selection of site for Buildings, Layout of Building Plan, Types of buildings, Plinth area, carpet area, floor space index, Introduction to building byelaws, concept of sun light & ventilation. Components of Buildings & their functions, Basic concept of R.C.C., Introduction to types of foundation
Chapter 5
Transportation: Introduction to Transportation Engineering; Traffic and Road Safety: Types and Characteristics of Various Modes of Transportation; Various Road Traffic Signs, Causes of Accidents and Road Safety Measures.
Chapter 6
Environmental Engineering: Environmental Pollution, Environmental Acts and Regulations, Functional Concepts of Ecology, Basics of Species, Biodiversity, Ecosystem, Hydrological Cycle; Chemical Cycles: Carbon, Nitrogen & Phosphorus; Energy Flow in Ecosystems.
Water Pollution: Water Quality standards, Introduction to Treatment & Disposal of Waste Water. Reuse and Saving of Water, Rain Water Harvesting. Solid Waste Management: Classification of Solid Waste, Collection, Transportation and Disposal of Solid. Recycling of Solid Waste: Energy Recovery, Sanitary Landfill, On-Site Sanitation. Air & Noise Pollution: Primary and Secondary air pollutants, Harmful effects of Air Pollution, Control of Air Pollution. . Noise Pollution Harmful Effects of noise pollution, control of noise pollution, Global warming & Climate Change, Ozone depletion, Greenhouse effect
Text Books:
1. Palancharmy, Basic Civil Engineering, McGraw Hill publishers.
2. Satheesh Gopi, Basic Civil Engineering, Pearson Publishers.
3. Ketki Rangwala Dalal, Essentials of Civil Engineering, Charotar Publishing House.
4. BCP, Surveying volume 1
How to Setup Warehouse & Location in Odoo 17 InventoryCeline George
In this slide, we'll explore how to set up warehouses and locations in Odoo 17 Inventory. This will help us manage our stock effectively, track inventory levels, and streamline warehouse operations.
How to Manage Your Lost Opportunities in Odoo 17 CRMCeline George
Odoo 17 CRM allows us to track why we lose sales opportunities with "Lost Reasons." This helps analyze our sales process and identify areas for improvement. Here's how to configure lost reasons in Odoo 17 CRM
A review of the growth of the Israel Genealogy Research Association Database Collection for the last 12 months. Our collection is now passed the 3 million mark and still growing. See which archives have contributed the most. See the different types of records we have, and which years have had records added. You can also see what we have for the future.
This presentation includes basic of PCOS their pathology and treatment and also Ayurveda correlation of PCOS and Ayurvedic line of treatment mentioned in classics.
Leveraging Generative AI to Drive Nonprofit InnovationTechSoup
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3. The Fine Structure of the
Nervous System
Neurons and Their Supporting Cells
Third Edition
ALAN PETERS
Waterhouse Professor of Anatomy, Department of Anatomy and Neurobiology
Boston University School of Medicine, Boston, Massachusetts
SANFORD L. PALAY
Bullard Professor of Neuroanatomy, Emeritus
Harvard Medical School, Boston, Massachusetts
HENRY DBF. WEBSTER
Chief, Laboratory of Experimental Neuropathology
National Institute of Neurological Diseases and Stroke, Bethesda, Maryland
New York Oxford OXFORD UNIVERSITY PRESS 1991
6. Preface
We wish to thank our many friends and colleagues who encouraged us to un-
dertake a third edition of this book on the fine structure of the nervous system.
This revision, like the previous editions (1970 and 1976), aims "to present in
words and pictures an account of the salient features of mammalian neurons
and neuroglial cells." We have thoroughly revised the text in order to bring it
up to date, and we have exchanged many of the original micrographs for ones
that we believe better show the characteristics of various structures. Through
the generosity of our colleagues, we have been able to add new freeze-fractured
material and some deep-etched preparations, as well as examples of various
labeling techniques. Consequently, the number of figures has increased from 118
to 137, and 51 of them are new illustrations.
Since the last edition was published there has been not only an information
explosion in neuroscience, but also a notable improvement in microtomes and
electron microscopes, so that the production of good electron micrographs poses
less of a challenge than it did even a decade ago. At the same time, however,
some of the "art" of electron microscopy has been lost. In the 1960s and early
1970s, when the technical demands of electron microscopy were greater, inves-
tigators devoted themselves wholeheartedly to acquiring the skills necessary for
producing electron micrographs that were both informative and esthetically at-
tractive. Sharp and clean images of well-fixed material were the aims of every
cytologist. Considerable effort was expended in the pursuit of the most complete
rendition of protoplasmic structure possible. Such images permitted neurocytol-
ogists to distinguish and describe all the components of the complex tissue that
the brain of any animal contains. Today, it is taken for granted that any study
that requires them can be illustrated with electron micrographs. But with the
increasing facility with the elementary techniques has come a decline in the ex-
acting criteria both for acceptable electron micrography and for credible inter-
pretation of the profiles displayed within them. Good examples of these changes
in standards can be found in the identification of synaptic junctions in tissues
taken from tracing experiments or from immunocytochemical studies. While this
vii
7. decline in standards is regrettable, it reflects the fact that electron microscopy of
the nervous system has passed the classic stage of exploration. Electron micro-
scopy is now being used to examine specific issues, such as the interconnections
among neurons and the locations of specific proteins or neuroactive substances.
Fifteen years ago we were using degeneration techniques and tracers, such as
horseradish peroxidase or radioactively labeled amino acids, in order to under-
stand how the nervous system is constructed. Although important information
was obtained through the use of these methods and they are still useful, their
place at the forefront has largely been ceded to intracellular filling techniques
and combined Golgi-electron microscopy. But the modern explosion in the neu-
romorphological sciences has been brought about by the use of antibodies to
identify the chemical signatures of neural pathways and individual neurons and
synaptic terminals. For all of these new approaches the appreciation of fine
structure is more pertinent than ever.
We have rewritten this book in the light of the information obtained through
the use of these newer methods because they have led to a much better under-
standing of the relationships between neuronal circuits and their functions. Con-
sequently we have extensively revised all of the chapters and added many new
references to the bibliography. We have, however, retained those references that
reflect the foundations upon which our new information is based. A reader fa-
miliar with the previous edition of this book will certainly recognize paragraphs
and descriptions that have not changed appreciably because no significant new
knowledge has come to our notice in that area. Other chapters, such as the
chapters on axons, synapses, sheaths, and the neuropil, have been almost en-
tirely rewritten. In the chapter on the neuropil we have tried to show the pos-
sibilities and limitations of the various techniques, so that this chapter has be-
come a vehicle for giving an account of the methods available. To a large extent
this strategy has allowed us to eliminate details of techniques from the other
chapters.
We hope that in this version of the book we have succeeded in correlating
structure and function and in providing a reference source of electron micro-
graphs and literature, in which both experienced neuroscientists and students
interested in the fine structure of the nervous system can find information be-
yond the scope of their immediate interests.
Although most of the illustrations come from our own collections, we have
relied on the generosity of many colleagues for illustrations of structures and
techniques that we have not explored ourselves. We gratefully acknowledge the
contributions of figures from J. Anders, D. J. Allen, Dennis Bray, Milton Bright-
man, Mary B. Bunge, Victoria Chan-Palay, M. W. Cloyd, Edward V. Famig-
lietti, Martin L. Feldman, James E. Hamos, C. K. Henrikson, John E. Heuser,
J. Hirokawa, James Kerns, Frank N. Low, Douglas L. Meinecke, Enrico Mug-
naini, Elio Raviola, Thomas S. Reese, Bruce Schnapp, Constantino Sotelo, Deb-
orah W. Vaughan, James E. Vaughn, Bruce W. Warr, and Raymond B. Wuer-
ker.
We are also grateful to Janet Harry, Mary Alba, Lilian Galloway and Joyce
Resil for typing the several versions of the manuscript and references, and to
Katherine Harriman, Karen Josephson and Claire Sethares for their expert tech-
nical assistance. In addition we wish to thank Dr. R. Hammer and Dr. V. J.
viii PREFACE
8. DeFeo for providing facilities for one of us (A.P.) to enjoy a session of quiet
writing at the University of Hawaii, and Dr. P. Hashimoto of Osaka University
for providing facilities for another of us (S.L.P.) during an extended visit.
By no means of least importance, we wish to pay tribute to our wives. With-
out their patience, understanding and support, we could not have completed
this revision.
Boston, Massachusetts Alan Peters
Concord, Massachusetts Sanford L. Palay
Bethesda, Maryland Henry deF. Webster
February 1990
PREFACE ix
9. Contents
List of Illustrations, xv
1 General Morphology of the Neuron, 3
2 The Neuronal Cell Body, 14
THE PERIKARYON, 14
The Nissl Substance, 14
The Agranular Reticulum, 22
The Golgi Apparatus, 26
Multivesicular Bodies, 33
Lysosomes, 33
Peroxisomes, 34
Lipofuscin Granules, 34
Mitochondria, 38
Microtubules and Neurofilaments, 40
Cilia and Centrioles, 41
Cytoplasmic Inclusions, 42
THE NUCLEUS, 48
General Morphology, 48
The Nuclear Envelope, 52
The Karyoplasm, 58
The Nucleolus, 59
Nuclear Inclusions, 60
THE PLASMA MEMBRANE, 64
3 Dendrites, 70
GENERAL MORPHOLOGY, 70
THE CYTOPLASM OF DENDRITES, 76
THE DENDRITIC SPINES, 82
MYELINATED DENDRITES, 96
GROWING TIPS OF DENDRITES, 98
xi
10. 4 The Axon, 101
AXON HILLOCK AND INITIAL AXON SEGMENT, 101
THE AXON BEYOND THE INITIAL SEGMENT, 108
Neurofilaments and Microtubules, 110
Membranous Components, 119
Cytoskeleton, 122
The Axonal Membrane, 124
AXOPLASMIC FLOW, 126
THE AXON GROWTH CONE, 132
THE IDENTIFICATION OF SMALL AXONS AND DENDRITES, 137
5 Synapses, 138
THE NEUROMUSCULAR SYNAPSE, 138
INTERNEURONAL CHEMICAL SYNAPSES, 147
The Synaptic Junction, 150
The Presynaptic Grid, 154
The Synaptic Cleft, 159
Potsysnaptic Densities, 160
Freeze-Cleavage, 166
Nonsynaptic Junctions Between Neurons, 168
Synaptic Vesicles With Clear Centers, 169
Shapes and Sizes of Vesicles, 169
Correlation Between Vesicle Shape and Function of Chemical Synapses, 176
Granular Vesicles, 178
Neurosecretory Vesicles, 184
Other Presynaptic Organelles, 186
Other Postsynaptic Organelles, 188
Synaptic Relations, 190
Axo-Dendritic Synapses, 190
Axo-Somatic Synapses, 191
Axo-Axonal Synapses, 192
Dendro-Dendritic Synapses, 195
Somato-Dendritic, Dendro-Somatic and Somato-Somatic Synapses, 196
Somato-Axonic Synapses, 198
Dendro-Axonic Synapses, 198
Synaptic Glomeruli, 199
ELECTROTONIC SYNAPSES, 203
MIXED SYNAPSES, 207
"SYNAPSES" INVOLVING NEUROGLIAL CELLS, 210
6 The Cellular Sheaths of Neurons, 212
THE SHEATHS OF UNMYELINATED GANGLION CELLS, 213
THE SHEATHS OF UNMYELINATED NERVE FIBERS, 218
THE SHEATHS OF MYELINATED FIBERS, 222
Internodal Peripheral Myelin, 224
The Formation of the Peripheral Myelin Sheath, 226
Internodal Central Myelin, 232
The Formation of the Central Myelin Sheath, 234
Identification of the Myelin-forming Cell of the Central Nervous System, 242
The Mechanism of Myelin Formation, 246
The Node of Ranvier, 250
The Schmidt-Lanterman Incisures, 261
xii CONTENTS
11. The Differences Between Peripheral and Central Myelin Sheaths, 262
The Proximity of Adjacent Sheaths, 262
The Thickness of Myelin Lamellae, 263
The Radial Component of the Central Sheath, 264
THE SHEATHS OF MYELINATED GANGLION CELLS, 265
MYELIN SHEATHS OF DENDRITES IN THE CENTRAL NERVOUS SYSTEM, 266
FUNCTIONS OF SATELLITE AND SCHWANN CELLS, 266
Early Development, 266
Axon Ensheathment and Myelin Formation, 267
Biochemical Relationships, 269
Breakdown of Myelin, 271
Other Functions, 272
7 The Neuroglial Cells, 273
THE DEVELOPMENT OF NEUROGLIA, 274
ASTROCYTES, 276
Fibrous Astrocytes, 277
Protoplasmic Astrocytes, 281
Functions of Astrocytes, 284
Structural Support, 284
Guidance for Neuroblast Migration and Axon Growth, 286
Graft Survival and Function, 288
Isolation of Receptive and Nodal Surfaces of Neurons, 288
Interactions with Oligodendroglia: Role in Myelination, 290
Blood-Brain Barrier, 290
Interactions with the Immune System, 293
Repair, 294
OLIGODENDROCYTES, 295
General Morphology, 295
Functions of Oligodendrocytes, 298
NEUROGLIAL CELLS INTERMEDIATE BETWEEN ASTROCYTES AND OLIGODENDROCYTES, 302
MICROGLIA, 304
General Morphology, 306
Functions, 308
Discussion, 308
8 The Ependyma, 312
THE MORPHOLOGY OF EPENDYMAL CELLS, 313
THE MORPHOLOGY OF TANYCYTES, 318
INTRAVENTRICULAR NERVE ENDINGS, 322
THE SUBEPENDYMA, 324
FUNCTIONS OF CELLS IN THE EPENDYMA, 325
Movements of Cerebrospinal Fluid, 325
Capture of Materials Present in the Cerebrospinal Fluid, 325
Proliferation, 325
Support, 326
Sensory Function, 326
Secretion, 326
Transport of Substances, 327
CONTENTS xiii
12. 9 Choroid Plexus, 328
THE CHOROIDAL EPITHELIUM, 330
THE VASCULARIZED CONNECTIVE TISSUE CORE, 336
FUNCTIONS OF THE CHOROID PLEXUS, 338
10 Blood Vessels, 344
CAPILLARIES, 344
ARTERIES AND ARTERIOLES, 350
VEINS, 354
11 The Neuropil, 356
THE IDENTIFICATION OF PROFILES IN THE NEUROPIL, 356
THE ORGANIZATION OF THE NEUROPIL AND SYNAPTIC CONNECTIONS, 364
Golgi—Electron Microscope Technique, 366
Intracellularly Injected Markers, 368
Reconstruction of Neurons and Their Processes, 370
Experimental Degeneration, 372
Intracellular Transport of Radioisotopes, 375
Antibodies to Neurotransmitters, 375
Antibodies to Neuropeptides, 380
Techniques Using Two Antibodies, 381
Combined Techniques, 382
12 Connective Tissue Sheaths of Peripheral Nerves, 384
EPINEURIUM, 384
PERINEURIUM, 385
ENDONEURIUM, 388
FUNCTIONS OF CONNECTIVE TISSUE SHEATHS, 392
13 The Meninges, 395
DURA MATER, 396
ARACHNOID MATER, 398
PIA MATER, 400
ENTRY OF PERIPHERAL NERVES INTO THE CENTRAL NERVOUS SYSTEM, 402
ARACHNOID VILLI, 404
References, 407 Index, 487
xiv CONTENTS
13. List of Illustrations
1-1 The Neuronal Cell Body, 11
2-1 The Cell Body of a Pyramidal Cell, 17
2-2 A Purkinje Cell, 19
2-3 Pyramidal Neuron, 21
2-4 Granule Cells of the Cerebellum, 23
2-5 The Cytoplasm of a Purkinje Cell, 25
2-6 The Cytoplasm of a Dorsal Root Ganglion Cell, 29
2-7 The Cytoplasm of a Dorsal Root Ganglion Cell, 31
2-8 Nissl Bodies in an Anterior Horn Cell, 35
2-9 The Golgi Apparatus and the Nissl Substance of a Purkinje Cell, 37
2-10 Golgi Apparatus of the Purkinje Cell, 39
2-11 Two Views of the Golgi Apparatus in a Freeze-Fractured Preparation, 43
2-12 Golgi Apparatus, Lysosomes, Nematosomes, and Fibrillary Inclusions, 45
2-13 Lipofuscin Granules, Cilia, and Centrioles, 47
2-14 Laminated Inclusion Body, 49
2-15 The Nuclear Envelope, Nissl Bodies, and Golgi Apparatus, 55
2-16 Nuclear Pores, 57
2-17 The Nucleolus, 61
2-18 Intranuclear Inclusions, 63
2-19 Diagram of Freeze Fracturing, 65
2-20 The Edge of a Purkinje Cell, Freeze-Fractured Preparation, 67
3-1 Pyramidal Neuron in Cerebral Cortex, 73
3-2 The Apical Dendrites of Pyramidal Cells, 75
3-3 Dendrite of a Purkinje Cell, 79
3-4 Dendrite of a Purkinje Cell, 81
3-5 Dendrites in Longitudinal and Transverse Section, 83
3-6 Dendrites in the Neuropil of the Anterior Horn: Transverse Section, 85
3-7 Dendrites in the Neuropil of the Cerebral Cortex, 87
3-8 Dendrites in Cerebellar and Cerebral Cortex, 89
3-9 A Spiny Branchlet of a Purkinje Cell Dendrite, 91
xv
14. 3-10 Olfactory Bulb, 93
3-11 Myelinated Dendrite in Olfactory Bulb, 97
3-12 Dendrite Growth Cones, 99
4-1 Axon Hillock and the Initial Axon Segment, 103
4-2 Axon Hillock and the Initial Axon Segment, 105
4-3 The Initial Axon Segment, Longitudinal Section, 107
4-4 The Initial Segment, Transverse Section, 109
4-5 The Initial Axon Segment and the Node of Ranvier Compared, 111
4-6 Axon Hillock and Initial Segment of a Trigeminal Ganglion Cell, 113
4-7 The Initial Segment of a Trigeminal Ganglion Cell, 115
4-8 Microtubules, Neurofilaments, and Neuroglial Filaments, 117
4-9 Axoplasmic Organelles, 121
4-10 Quick-frozen and Deep-etched Axoplasm, 123
4-11 Quick-frozen and Deep-etched Axoplasm, 125
4-12 Growth Cone from a Sympathetic Neuron in Tissue Culture, 129
4-13 Growth Cone from a Sympathetic Neuron in Tissue Culture, 131
4-14 Small Axons in the Molecular Layer of the Cerebellum, 133
4-15 Unmyelinated Axons Entering the Olfactory Bulb, 135
5-1 Motor End Plate, 141
5-2 Motor End Plate, 143
5-3 Freeze-Fractured Motor End Plates to Show Vesicle Release, 145
5-4 Puncta Adhaerentia, 149
5-5 Axon Terminal Emerging from the Myelin Sheath, 151
5-6 Synapses in the Cerebral Cortex, 153
5-7 Asymmetric Synapses, Cerebral Cortex, 155
5-8 Presynaptic Grid, 157
5-9 Synapses in the Cerebellum, 161
5-10 The Synaptic Junction Between an Axon and a Dendritic Thorn, 163
5-11 Asymmetric and Symmetric Synapses, 165
5-12 Synapses in the Anterior Horn of Spinal Cord, 167
5-13 Anterior Horn of Spinal Cord, 171
5-14 The Glomerulus, Cerebellar Cortex, 173
5-15 The Presynaptic Membrane, P face, 175
5-16 The Presynaptic Membrane, E face, 181
5-17 A Variety of Synapses, 183
5-18 Axo-axonic Synapse and Dense-cored Vesicles, 185
5-19 Dendro-dendritic and Somato-dendritic Synapses, 189
5-20 The Glomerulus, Lateral Geniculate Nucleus, 197
5-21 Electrotonic Synapses, 205
5-22 A Mixed Synapse, 209
6-1 The Sheath Surrounding a Dorsal Root Ganglion Cell, 215
6-2 The Sheath Surrounding a Trigeminal Ganglion Cell, 217
6-3 Unmyelinated Axons, Adult Peripheral Nerve, 219
6-4 Unmyelinated Axons, Adult Peripheral Nerve, 221
6-5 Myelinated Axon, Adult Peripheral Nerve, 227
xvi ILLUSTRATIONS
15. 6-6 Developing Schwann Cell Sheaths, 229
6-7 Developing Schwann Cell Sheaths, Later Stage, 231
6-8 Diagrammatic Representation of the Formation of Peripheral Myelin Sheaths, 233
6-9 Myelinated Nerve Fibers, Central Nervous System, 235
6-10 Myelin Sheaths: Central Nervous System, 237
6-11 Developing Myelin Sheaths, Central Nervous System, 239
6-12 Developing Myelin Sheaths, Central Nervous System, 241
6-13 Diagrammatic Representation of the Formation of Myelin in the Central Nervous System, 243
6-14 The Myelin Forming Cell, Central Nervous System, 245
6-15 The Node of Ranvier, Peripheral Nervous System, 249
6-16 The Node of Ranvier, Central Nervous System, 251
6-17 The Node and the Paranode, Central Nervous System, 253
6-18 Freeze-Fractured Myelin Sheaths, 255
6-19 Freeze-Fractured Myelin Sheaths, 257
6-20 Freeze-Fractured Myelin Sheaths, 259
6-21 Diagram of Membrane Particle Distribution at the Paranode, 260
7-1 Fibrous Astrocytes, 279
7-2 Protoplasmic Astrocytes, 283
7-3 Protoplasmic Astrocytes, 285
7-4 Protoplasmic Astrocyte, 287
7-5 Glial Limiting Membrane; Cerebral Cortex, 289
7-6 Orthogonal Assemblies and Gap Junctions of Astrocytes in Freeze-Fracture Preparations, 291
7-7 Perineuronal Oligodendrocytes, 297
7-8 An Oligodendrocyte, 299
7-9 Interfascicular Oligodendrocyte, 301
7-10 A Perineuronal Microglial Cell, 303
7-11 A Microglial Cell in a Senile Plaque, 307
8-1 The Ependyma, 315
8-2 Ependymal Surface, 317
8-3 The Cilia of Ependymal Cells, 319
8-4 Ependymal Cell Cytoplasm, 321
8-5 Ependymal Cell Junctions, 323
9-1 Scanning Electron Micrograph of the Choroid Plexus, 329
9-2 Epithelium and Stroma of the Choroid Plexus, 331
9-3 The Choroid Plexus, 333
9-4 Choroid Plexus, Intercellular Junctions, 335
9-5 Choroid Plexus, Intercellular Junctions, 337
9-6 Choroid Plexus, Surface Structures, 339
9-7 The Basal Ends of Choroidal Cells, 341
9-8 Kolmer Cells, 343
10-1 Capillary and Pericyte, 347
10-2 Capillaries, 349
10-3 Small Blood Vessel, 351
10-4 Intracerebral Arterioles, 353
10-5 An Arteriole, 355
ILLUSTRATIONS xvii
16. 11-1 The Neuropil, Anterior Horn, Spinal Cord, 359
11-2 The Neuropil, Cerebellar Cortex, 361
11-3 The Neuropil, Cerebral Cortex, 363
11-4 Lateral Geniculate Body Glomerulus, 365
11-5 Degenerating Boutons, 367
11-6 Filamentous Degeneration and Horseradish Peroxidase-labeled Neurons, 369
11-7 Golgi-Electron Microscope Technique, 371
11-8 Intracellular Horseradish Peroxidase Injection, 373
11-9 Glutamic Acid Decarboxylase Immunoreactive Axon Terminals, 377
11-10 Vasoactive Intestinal Polypeptide in the Cerebral Cortex, 379
12-1 Connective Tissue Sheaths of Nerves, 387
12-2 Epineurial and Perineurial Sheaths, 389
12-3 Perineurium and Endoneurium of Peripheral Nerve, 391
13-1 Meninges by Scanning Electron Microscopy, 397
13-2 Dura Mater, 399
13-3 Arachnoid Mater, 401
13-4 Pia Mater and Glia Limitans, 403
xviii ILLUSTRATIONS
17. Dedicated to the Memory of
Jan Evangelista Purkinje, 1787-1869
Louis-Antoine Ranvier, 1835-1922
Camillo Golgi, 1843-1926
Santiago Ramon у Cajal, 1852-1934
19. 1
General Morphology of
the Neuron
Anyone who has studied the early history of cy- nervous system lay in the shape of the nerve cell
tology cannot fail to be impressed by the slow itself and to some extent in its size. The medusa-
development of the concept of the nerve cell. Most like nerve cell, with its corona of seemingly endless
types of cells do not have a history. Once the idea processes, was bizarre. Other cells had relatively
was grasped, in the theory of Schleiden (1838) simple shapes—globular, cylindrical, squamous,
and Schwann (1839), that cells are the architec- fusiform, and so on. Some fitted one into the other
tonic units of living things, it was fairly quick like pieces of a jigsaw puzzle to form an epithe-
work to recognize them in the various tissues and lium; others lay free and definable in the tissue
to proceed to the study of their contents, their fluids. Many, such as cartilage or certain epithelial
interrelations, and their functions. But the nerve cells, were clearly circumscribed by walls. Only
cell was more perplexing. It occasioned so much pigment cells, astrocytes, myoepithelial cells, and
difficulty for its students that almost a century a few others had shapes even roughly approxi-
passed before they could agree upon its shape. At mating those of nerve cells. But aside from the
first it was thought to be an independent globular fact that some of these examples were unknown
corpuscle suspended among nerve fibers, which in the early days, such cells could be easily encom-
looped and coiled about it and which it somehow passed in a single field or at least in a single
nourished (Valentine, 1836). Later, when the con- preparation under the microscope. The multipolar
tinuity between the perikaryon and the nerve fi- nerve cell, however, with its meter-long axon did
bers was finally established (Remak, 1838, 1841; not fit into a single section and could not be easily
Helmholtz, 1842; Hannover, 1844; Kolliker, 1844; plucked from its context or distinguished from its
Bidder, 1847; Wagner, 1847), then the nerve cell neighbors by the methods used for other cells.
appeared to have no definite boundaries and seemed New methods had to be developed. And so a true
endless. Except for the fibers attached to organs cell theory of the nervous system did not emerge
in the periphery, the processes of all nerve cells until the discovery and exploitation of special
seemed to be equivalent and to be confluent with techniques that had the merit of bringing into
one another. The nerve cells seemed to be only view entire nerve cells as if dissected or isolated
nodal points in an enormously intricate reticulum from the central nervous system.
pervading the nervous system (Gerlach, 1858, Actually, the first successful method was mi-
1872). It appeared that the cell theory did not crodissection of whole nerve cells from hardened
really apply to the nervous system; one had rather specimens of brain and spinal cord. On the basis
to speak of cell territories or spheres of influence of experience with such isolated cells, Deiters (1865)
surrounding nucleated centers. was able to distinguish between the numerous
It seems clear that one of the major obstacles branching processes that we now call dendrites
to the appreciation of the cellular nature of the and the single process that slips into a myelin
3
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