This document summarizes a study that used genetic fate mapping to track the cell lineages derived from cells expressing the Hox gene Hoxa5 in mouse embryo somites. The study found that Hoxa5-expressing cells give rise to dermis, perichondria, adipocytes, and neurons at early stages, but also contribute to chondrocytes at later stages. Specifically, Hoxa5 descendants were not present in vertebral bodies at e9.5, suggesting chondrocytes do not express Hoxa5 until after e10.5. This fate mapping analysis provides insight into how Hoxa5 patterns regional identity in the developing musculoskeletal system in a tissue- and time-dependent manner.
The document summarizes regulation of Sertoli cell dynamics in the testis. Key points include:
- Sertoli cells are the first somatic cells to differentiate in the embryonic testis under control of the Sry gene. They express factors that establish testis morphology.
- Sertoli cells proliferate during fetal and prepubertal development, then exit the cell cycle at puberty. The number of Sertoli cells determined at puberty sets the limit for sperm production.
- Several factors influence Sertoli cell proliferation and maturation, including FSH, testosterone, retinoic acid, thyroid hormone, growth factors, and cell junction proteins. The effects of these factors are stage-specific
This document summarizes key concepts from a lecture on reproductive physiology:
1) It describes the cumulus oophorus and corona radiata, cells surrounding the ovum that are released during ovulation and may help with fertilization.
2) It provides a table summarizing reproductive hormones including their biological class, source, target tissues, and primary actions in males and females.
3) It discusses endocrine mechanisms involved in processes like the estrous cycle, pregnancy, and testicular functions. Growth factors that regulate reproduction are also outlined.
The cerebellum plays an important role in motor control and coordination. It receives sensory input from various parts of the brain and spinal cord, and integrates this information to fine tune motor activity. The cerebellum contains three lobes and several types of neurons that allow it to modulate motor signals from the brain. Purkinje cells, granule cells, and various fiber types help process sensory signals and regulate motor output through the deep cerebellar nuclei.
This document discusses gametogenesis and spermatogenesis. It describes the four phases of gametogenesis as the formation and migration of primordial germ cells, mitotic increase in germ cell numbers, meiotic reduction in DNA content, and differentiation and maturation. It then focuses on spermatogenesis, outlining the stages from spermatogonia to spermatozoa. Key events of spermiogenesis like nuclear shaping, flagellum formation, and acrosome formation are noted. The role of dynein ATPase in regulating sperm motility and the roles of calcium and pH are summarized.
The development of the tetrapod limb involves specification of the limb field and induction of the early limb bud through FGF10 signaling. The proximal-distal axis is established by the AER, which secretes FGF8 to maintain the progress zone. The anterior-posterior axis is specified by SHH expression in the ZPA. The dorsal-ventral axis forms through Wnt7a expression on the dorsal side. Cell death regulated by BMPs then separates the digits and forms joints.
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The document discusses the endocrine and nervous systems and how they relate and differ. It explains that the endocrine system uses hormones to regulate slower biological processes like growth, while the nervous system regulates faster processes using electrical impulses. Both systems can influence reproduction and development through integration of their signals. Specific examples are given of hormones that regulate molting, metamorphosis, and reproduction in various organisms.
The document summarizes regulation of Sertoli cell dynamics in the testis. Key points include:
- Sertoli cells are the first somatic cells to differentiate in the embryonic testis under control of the Sry gene. They express factors that establish testis morphology.
- Sertoli cells proliferate during fetal and prepubertal development, then exit the cell cycle at puberty. The number of Sertoli cells determined at puberty sets the limit for sperm production.
- Several factors influence Sertoli cell proliferation and maturation, including FSH, testosterone, retinoic acid, thyroid hormone, growth factors, and cell junction proteins. The effects of these factors are stage-specific
This document summarizes key concepts from a lecture on reproductive physiology:
1) It describes the cumulus oophorus and corona radiata, cells surrounding the ovum that are released during ovulation and may help with fertilization.
2) It provides a table summarizing reproductive hormones including their biological class, source, target tissues, and primary actions in males and females.
3) It discusses endocrine mechanisms involved in processes like the estrous cycle, pregnancy, and testicular functions. Growth factors that regulate reproduction are also outlined.
The cerebellum plays an important role in motor control and coordination. It receives sensory input from various parts of the brain and spinal cord, and integrates this information to fine tune motor activity. The cerebellum contains three lobes and several types of neurons that allow it to modulate motor signals from the brain. Purkinje cells, granule cells, and various fiber types help process sensory signals and regulate motor output through the deep cerebellar nuclei.
This document discusses gametogenesis and spermatogenesis. It describes the four phases of gametogenesis as the formation and migration of primordial germ cells, mitotic increase in germ cell numbers, meiotic reduction in DNA content, and differentiation and maturation. It then focuses on spermatogenesis, outlining the stages from spermatogonia to spermatozoa. Key events of spermiogenesis like nuclear shaping, flagellum formation, and acrosome formation are noted. The role of dynein ATPase in regulating sperm motility and the roles of calcium and pH are summarized.
The development of the tetrapod limb involves specification of the limb field and induction of the early limb bud through FGF10 signaling. The proximal-distal axis is established by the AER, which secretes FGF8 to maintain the progress zone. The anterior-posterior axis is specified by SHH expression in the ZPA. The dorsal-ventral axis forms through Wnt7a expression on the dorsal side. Cell death regulated by BMPs then separates the digits and forms joints.
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The document discusses the endocrine and nervous systems and how they relate and differ. It explains that the endocrine system uses hormones to regulate slower biological processes like growth, while the nervous system regulates faster processes using electrical impulses. Both systems can influence reproduction and development through integration of their signals. Specific examples are given of hormones that regulate molting, metamorphosis, and reproduction in various organisms.
The document outlines a business plan for an outdoor media marketplace in Pakistan. It notes key problems like a lack of available media information and high agency commissions. The proposed solution is an online platform that lists available media for buyers and sellers, making outdoor media sharing easy. It aims to serve both media owners and advertisers, reaching small and large clients. Initial funding would support hiring staff and product development to build the minimum viable product.
This document provides instructions for building a low-cost wireless router using old computer parts and a Mikrotik router operating system. The necessary components include a motherboard, RAM, hard drive, network card, wireless miniPCI card, and power supply. It estimates the total cost to be around 1 million Rupiah. It describes installing the components and Mikrotik OS, then configuring the wireless settings following Mikrotik's online instructions. The goal is to create an affordable wireless access point for small networks or internet sharing.
Dokumen ini berisi latihan mengidentifikasi dan memadankan nama-nama warna dalam bahasa Melayu. Terdapat serangkaian soalan yang memerlukan pengguna untuk memadankan nama-nama warna seperti merah, kuning, biru, hijau, dan sebagainya.
This document summarizes a gastroenterologist's perspective on the field of gastroenterology. It discusses how gastroenterology combines both the science and art of medicine. The science involves understanding the microscopic functions of the gut and how stress can affect gastrointestinal symptoms. However, diagnosing and treating gastrointestinal illnesses also requires understanding the patient's life context and experiences. This blending of the objective biological factors with the individual patient is what makes gastroenterology both challenging and rewarding. The document emphasizes the importance of effective communication and developing a trusting relationship with patients, especially those suffering from chronic or complex conditions.
Bitcoin and CrowdFunding - Bitcoinference Summer 2014Sigimera
The document discusses how bitcoin and crowd-funding can be combined to help a person named Bob fund a project, though financial institutions are still involved and micropayments using bitcoin are instantaneous. It proposes developing this idea further by integrating bitcoin and social networks for simpler crowdfunding through a site called BTC-Funding.com.
The document is a newspaper from Ardsley High School that discusses several topics:
- The drama club's performance of Little Shop of Horrors, praising the cast and realistic set and props.
- The work of the school's Habitat for Humanity club, which builds homes for those in need at least twice a month. The club aims to both help people and raise awareness of poverty within Westchester County.
- A talk given at the school by an IBM researcher about Watson, the question-answering computer system, and its potential applications in healthcare. Students debated whether they would feel comfortable being diagnosed by a machine.
Two Ardsley High School seniors, Victoria Sheridan and Annie Sourbis, spent their senior externship creating a prom dress entirely out of duct tape as a personal interest project. They received approval from the school to spend over 100 hours designing and crafting the dress and accessories like a clutch, corsage, and shoes covered in duct tape. Many doubted they could complete the project, but the girls persevered and finished the dress just before prom. They hope to bring fun and uniqueness to formal events through their non-traditional duct tape design.
'Top 9 Festive Foods' RE: Digital Publishing.sinheadd
This document provides recipes for 9 festive foods and drinks for Christmas, including goat cheese and chutney, Baileys hot chocolate, Eton mess, chocolate covered saltine crackers, rice crispy cakes, cranberry and orange vodka cocktail, and mulled wine. For each item, a brief description is given along with a link to find the full recipe on an external website. The foods include starters, main dishes, desserts, snacks, and festive cocktails suitable for the Christmas season.
Networld R&D is an incubator project sponsored by Sigimera Ltd that started in 2006 as a BitTorrent tracker and has expanded to include projects such as MokSec in 2008, Android app development in 2010, and launching a Platform as a Service in 2014. The document provides an overview of Networld R&D's timeline and projects as well as contact information.
This document provides an introduction to Bitcoin, including how it works as a payment network and new type of currency. It explains that Bitcoin users create addresses to receive funds and that senders transfer amounts to those addresses. The transactions are then confirmed by miners through mathematical calculations before funds are available to spend. The document also outlines some common questions about Bitcoin wallets, transactions, and mining. It encourages testing Bitcoin functionality on testnet wallets.
Latest Advances in GPS technology Seminar reportMode Gautam Raj
The document summarizes the latest advances in GPS technology. It provides an overview of how GPS works with 24 satellites that orbit Earth and transmit radio signals. A GPS receiver can locate 4 or more satellites to calculate the user's position via trilateration. The document then describes the 3 segments of GPS - the space segment consisting of satellites, the control segment that tracks satellites, and the user segment of receivers. It outlines objectives of GPS for military like navigation and targeting, and for other uses such as automotive navigation, aviation, agriculture, and disaster relief.
The document discusses myogenesis, or muscle formation, which occurs through somitogenesis. Mesoderm forms somites through periodic segmentation. Somites give rise to muscle precursor cells (myoblasts) that require growth factors and transcription factors like MyoD to differentiate into muscle cells. Myoblasts align and fuse to form multinucleated myotubes. Satellite cells reside alongside adult muscle fibers and regenerate muscle through similar myogenic pathways upon injury.
1) Evolutionary developmental biology studies how developmental mechanisms drive evolutionary change by comparing development across organisms.
2) Genetic changes influence morphology through controlling growth rates and timing of development. Variation in developmental genes like Hox and Pax6 affect traits and can lead to new species.
3) Differences in expression of BMP4 and Gremlin proteins during chicken and duck foot development led to webbed versus non-webbed feet, demonstrating how development influences evolution.
The document outlines a business plan for an outdoor media marketplace in Pakistan. It notes key problems like a lack of available media information and high agency commissions. The proposed solution is an online platform that lists available media for buyers and sellers, making outdoor media sharing easy. It aims to serve both media owners and advertisers, reaching small and large clients. Initial funding would support hiring staff and product development to build the minimum viable product.
This document provides instructions for building a low-cost wireless router using old computer parts and a Mikrotik router operating system. The necessary components include a motherboard, RAM, hard drive, network card, wireless miniPCI card, and power supply. It estimates the total cost to be around 1 million Rupiah. It describes installing the components and Mikrotik OS, then configuring the wireless settings following Mikrotik's online instructions. The goal is to create an affordable wireless access point for small networks or internet sharing.
Dokumen ini berisi latihan mengidentifikasi dan memadankan nama-nama warna dalam bahasa Melayu. Terdapat serangkaian soalan yang memerlukan pengguna untuk memadankan nama-nama warna seperti merah, kuning, biru, hijau, dan sebagainya.
This document summarizes a gastroenterologist's perspective on the field of gastroenterology. It discusses how gastroenterology combines both the science and art of medicine. The science involves understanding the microscopic functions of the gut and how stress can affect gastrointestinal symptoms. However, diagnosing and treating gastrointestinal illnesses also requires understanding the patient's life context and experiences. This blending of the objective biological factors with the individual patient is what makes gastroenterology both challenging and rewarding. The document emphasizes the importance of effective communication and developing a trusting relationship with patients, especially those suffering from chronic or complex conditions.
Bitcoin and CrowdFunding - Bitcoinference Summer 2014Sigimera
The document discusses how bitcoin and crowd-funding can be combined to help a person named Bob fund a project, though financial institutions are still involved and micropayments using bitcoin are instantaneous. It proposes developing this idea further by integrating bitcoin and social networks for simpler crowdfunding through a site called BTC-Funding.com.
The document is a newspaper from Ardsley High School that discusses several topics:
- The drama club's performance of Little Shop of Horrors, praising the cast and realistic set and props.
- The work of the school's Habitat for Humanity club, which builds homes for those in need at least twice a month. The club aims to both help people and raise awareness of poverty within Westchester County.
- A talk given at the school by an IBM researcher about Watson, the question-answering computer system, and its potential applications in healthcare. Students debated whether they would feel comfortable being diagnosed by a machine.
Two Ardsley High School seniors, Victoria Sheridan and Annie Sourbis, spent their senior externship creating a prom dress entirely out of duct tape as a personal interest project. They received approval from the school to spend over 100 hours designing and crafting the dress and accessories like a clutch, corsage, and shoes covered in duct tape. Many doubted they could complete the project, but the girls persevered and finished the dress just before prom. They hope to bring fun and uniqueness to formal events through their non-traditional duct tape design.
'Top 9 Festive Foods' RE: Digital Publishing.sinheadd
This document provides recipes for 9 festive foods and drinks for Christmas, including goat cheese and chutney, Baileys hot chocolate, Eton mess, chocolate covered saltine crackers, rice crispy cakes, cranberry and orange vodka cocktail, and mulled wine. For each item, a brief description is given along with a link to find the full recipe on an external website. The foods include starters, main dishes, desserts, snacks, and festive cocktails suitable for the Christmas season.
Networld R&D is an incubator project sponsored by Sigimera Ltd that started in 2006 as a BitTorrent tracker and has expanded to include projects such as MokSec in 2008, Android app development in 2010, and launching a Platform as a Service in 2014. The document provides an overview of Networld R&D's timeline and projects as well as contact information.
This document provides an introduction to Bitcoin, including how it works as a payment network and new type of currency. It explains that Bitcoin users create addresses to receive funds and that senders transfer amounts to those addresses. The transactions are then confirmed by miners through mathematical calculations before funds are available to spend. The document also outlines some common questions about Bitcoin wallets, transactions, and mining. It encourages testing Bitcoin functionality on testnet wallets.
Latest Advances in GPS technology Seminar reportMode Gautam Raj
The document summarizes the latest advances in GPS technology. It provides an overview of how GPS works with 24 satellites that orbit Earth and transmit radio signals. A GPS receiver can locate 4 or more satellites to calculate the user's position via trilateration. The document then describes the 3 segments of GPS - the space segment consisting of satellites, the control segment that tracks satellites, and the user segment of receivers. It outlines objectives of GPS for military like navigation and targeting, and for other uses such as automotive navigation, aviation, agriculture, and disaster relief.
The document discusses myogenesis, or muscle formation, which occurs through somitogenesis. Mesoderm forms somites through periodic segmentation. Somites give rise to muscle precursor cells (myoblasts) that require growth factors and transcription factors like MyoD to differentiate into muscle cells. Myoblasts align and fuse to form multinucleated myotubes. Satellite cells reside alongside adult muscle fibers and regenerate muscle through similar myogenic pathways upon injury.
1) Evolutionary developmental biology studies how developmental mechanisms drive evolutionary change by comparing development across organisms.
2) Genetic changes influence morphology through controlling growth rates and timing of development. Variation in developmental genes like Hox and Pax6 affect traits and can lead to new species.
3) Differences in expression of BMP4 and Gremlin proteins during chicken and duck foot development led to webbed versus non-webbed feet, demonstrating how development influences evolution.
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Paraxial mesoderm forms somites along the spine through somitogenesis. Somites differentiate into sclerotome, dermamyotome and myotome tissues. Sclerotome forms cartilage and bone of the vertebrae. Dermamyotome forms dermis and muscle lineages. Myotome separates into epaxial and hypaxial regions that form back muscles and body wall muscles. Intermediate mesoderm forms the urogenital system including pronephros, mesonephros and metanephros kidneys as well as gonads. The metanephros is the permanent kidney in amniotes.
- Limb development begins in the 4th week of gestation from lateral plate mesoderm under the guidance of three signaling centers: the AER, ZPA, and dorsal/ventral ectoderm.
- The AER guides proximal-distal growth through FGF signaling, the ZPA patterns anterior-posterior development using SHH, and the ectoderm determines dorsal-ventral fates through WNT7a.
- Failure of limb formation can result in transverse or longitudinal deficiencies, where parts of the limb fail to develop fully, such as in radial club hand where the radius is absent. Classification systems aim to describe the spectrum of abnormalities.
This document discusses genes, DNA, and development. It explains that DNA contains genes which make up our genotype that is passed down from our parents. Gene expression and inheritance can occur through different patterns like dominant/recessive, co-dominance, and sex-linked traits. Abnormalities in genes and chromosomes can result in hereditary disorders involving extra or missing chromosomes, including common sex chromosome disorders and Down syndrome. Methods like amniocentesis are used to detect abnormalities, while genetics also influences traits like intelligence and mental health.
Homeobox genes are a large family of genes that regulate embryonic development. They were first discovered in fruit flies and contain a DNA sequence called the homeodomain that encodes a protein regulating transcription of other genes. In humans, homeobox genes are organized into four clusters (A-D) on different chromosomes and regulate body patterning along the head-to-tail axis. Mutations in homeobox genes can lead to developmental disorders like aniridia, synpolydactyly, and Axenfeld-Rieger syndrome. There is potential to use homeobox genes like PDX-1 in gene therapy to generate new tissues like pancreatic beta cells in the liver to treat diseases like diabetes.
Homeobox genes are a large family of genes that regulate embryonic development. They were first discovered in fruit flies and contain a DNA sequence called the homeodomain that encodes a protein regulating gene expression. In humans, homeobox genes are organized into four clusters (A-D) on different chromosomes and regulate body patterning along the anterior-posterior axis. Mutations in homeobox genes can lead to developmental disorders like aniridia, synpolydactyly, and Axenfeld-Rieger syndrome. Genetic engineering using homeobox genes may enable creating new organs from a person's own tissues.
This document provides an overview of the endocrine system. It discusses how hormones act as chemical messengers that are secreted into the bloodstream and carried to target tissues. There are three main types of hormone receptors: G-protein coupled receptors, enzyme receptors, and receptors associated with ion channels. The major classes of hormones include peptide hormones, steroid hormones, and amine hormones. The hypothalamus and pituitary gland form the hypothalamic-pituitary axis that regulates many endocrine functions. The posterior pituitary stores and releases oxytocin and antidiuretic hormone, which are involved in uterine contraction, milk release, and water balance.
Homeotic genes are master regulatory genes that control body pattern formation during early embryonic development. Each homeotic gene encodes a transcription factor protein that induces downstream gene networks involved in body patterning. Mutations in homeotic genes can cause homeosis, where body parts develop in abnormal places, and ectopic structures are often lethal. Examples include Drosophila genes like the Antennapedia complex that affect the development of antennae versus legs when mutated. Homeotic genes are highly conserved across animals and play an important role in determining body segment identity and patterning during embryonic development.
Homeotic genes, such as Hox genes, direct embryonic development by regulating the formation of body structures. In fruit flies, mutations in homeotic genes can result in abnormal growth like legs on the head. Researchers like Lewis, Wieschaus, and Nüsslein-Volhard discovered the role of homeotic genes in fly development and were awarded the Nobel Prize. Homeotic genes are conserved across species and in humans are organized into four clusters that guide development along the head-to-tail axis.
Hox genes allow animals to have complex body plans with specialized segments through their controlled expression patterns. A diverse range of regulatory mechanisms, including nuclear dynamics, RNA processing, microRNAs, and translational control, work together to ensure robust Hox gene expression during development. Disruptions to this complex multi-tiered regulation of Hox genes can lead to developmental defects.
The document discusses the molecular regulation of neural induction and neurulation. It explains that upregulation of FGF signaling and inhibition of BMP4 activity causes ectoderm to become neural tissue by default. During neurulation, the neural plate forms the neural tube as the neural folds fuse in the midline. Neural crest cells emerge and migrate throughout the embryo to form many tissues. Precise regulation of BMP concentrations induces different cell fates in the ectoderm.
Paraxial and intermediate mesoderm form important structures. Paraxial mesoderm forms somites through a "clock and wave" mechanism, with each somite giving rise to vertebrae, muscle, and dermis. Somites are specified by surrounding tissues to develop appropriately. Intermediate mesoderm forms the kidney, with the pronephros, mesonephros, and metanephros appearing sequentially in vertebrate development. The metanephros becomes the permanent kidney in amniotes.
The document provides information about male and female reproductive physiology:
I. It describes the process of spermatogenesis that occurs in the seminiferous tubules of the testes to produce sperm over 65-75 days.
II. It explains the hormonal regulation of the male reproductive system including the roles of FSH, LH, and testosterone.
III. It outlines the female reproductive cycle over approximately 28 days, including the ovarian cycle, uterine cycle, and hormonal changes (FSH, LH, estrogens, progesterone) that regulate the growth and shedding of the endometrium.
This document discusses evolutionary developmental biology and how changes in development can lead to evolutionary changes. It provides examples of modularity and molecular parsimony which help explain this. Modularity means parts of the body and DNA can develop differently. Molecular parsimony means organisms share developmental toolkit genes. The document then discusses specific examples like stickleback fish pelvic spines being due to different Pitx1 expression, and Darwin's finches having beak shape variations due to differing Bmp4 and Calmodulin expression levels. Mechanisms of evolutionary change include changes in location, timing, amount, or kind of gene expression.
This document provides an overview of hormones and the endocrine system. It discusses the structure and functions of the endocrine system, including how hormones are produced by endocrine glands and target specific tissues through receptor binding. The key endocrine glands are identified as the hypothalamus, pituitary gland, thyroid gland, parathyroid glands, adrenal glands, pancreas, ovaries and testicles. The document also defines endocrinology as the science studying the mechanisms controlling hormone synthesis, release, transport, and actions in regulating physiological responses in target tissues.
T1L1 ORGANIZATION OF THE HYPOTHALAMUS, PITUITARY AND PINEAL GLANDS.pptxStanleyOdira
The hypothalamus regulates homeostasis through various nuclei that control functions like feeding, thermoregulation and circadian rhythms. It communicates with the pituitary via hormones to regulate endocrine axes. The pituitary contains tropic cells that secrete hormones under hypothalamic influence to regulate other endocrine glands. The pineal gland releases melatonin in response to darkness, synchronizing circadian rhythms and metabolic processes.
Arnold Berthold conducted early endocrine experiments in 1849 showing that castration caused changes in roosters that could be reversed by testicular extracts, demonstrating the endocrine role of the testes. Claude Bernard established that hormones travel via blood to regulate the internal environment. The endocrine and nervous systems both integrate stimuli and responses but differ in their modes of communication. Hormones are categorized into peptides/proteins, amino acid derivatives, steroids, and fatty acid derivatives. Key aspects of hormone function, synthesis, regulation, and control are discussed.
Similar to Dima Chaar Senior Thesis presentation (20)
2. What are Hox genes?
• Hox genes encode Transcription Factors
• Transcription factors are proteins that
bind and control the activity of other
genes
• The combination of Hox genes expressed
in embryonic musculoskeletal and neural
tissues specifies regional identity of
those tissues along head-to-tail axis
• Hox mutations lead to homeotic
transformations
3. Role of Hox genes in Development
• During development,
• Most of the musculoskeletal
system arises from somites
• The brain and spinal cord arise
from the neural tube
• Somites compartmentalize and
their derivatives differentiate
• Hox genes are expressed in the
somites and neural tube,
where they regulate regional
identity
Dermomyotomeà
• Dermis
• Muscle
• Muscle Connective
Tissue
• Adipocytes
Sclerotomeà
• Chondrocytes
(cartilage)
• Perichondrium
• Ligaments
• Tendons
Neural Tubeà
• Neurons
4. My focus: Hoxa5
• Hoxa5 expression occurs in the
cervical-to-thoracic transition in
somites
• Hoxa5 is required for regionalization of
the musculoskeletal and nervous
systems in the same area
• I will be focusing on Hoxa5’s role in
somite differentiation
5. • We know:
• Where Hoxa5 is expressed
• What roles Hoxa5 performs in vertebral development from studies of
loss-of-function mutations
• We don’t know:
• How Hoxa5 plays its crucial role in vertebral development
• Which tissues are derived from Hoxa5-expressing cells and when is Hoxa5
expression necessary?
• Transcriptional targets
11. Experiment 1: Generate embryos in
which the Hoxa5 -
expressing cells and
their descendants are
labelled with Tdtomato
Inject Tamoxifen
at specific dose
(9, 12 or 15 mg/40mg)
Harvest and
embed embryos
in OCT
Section with
cryostat
Immuno-
histochemistry
Microscopy and
Photography
At e8.5
At e14.5
Choose Tamoxifen dose with
• Adequate Tdtomato
labeling
• Embryos survive
25. Tissue Types e9.5 e12.5 e13.5
Chondrocytes No Yes Yes
Perichondria Yes Yes Yes
Muscle Fibroblasts Yes Yes Yes
Dermis Yes Yes Yes
Adipocytes Yes Yes Yes
Neurons Yes Yes Yes
Tamoxifen Injection Time Points
• Hoxa5-expressing cells gave rise to dermis, perichondria
and adipocytes at e9.5-13.5
26. Tissue Types e9.5 e12.5 e13.5
Chondrocytes No Yes Yes
Perichondria Yes Yes Yes
Muscle Fibroblasts Yes Yes Yes
Dermis Yes Yes Yes
Adipocytes Yes Yes Yes
Neurons Yes Yes Yes
Tamoxifen Injection Time Points
• The absence of descendants in the vertebral body at e9.5
suggests that chondrocytes do not express Hoxa5 until after
e10.5.
29. Implications
• Studying the role of Hoxa5 is crucial to understanding
• Complexities behind embryological development
• How early mutations could lead to physical abnormalities
and health defects
• With this information, future doctors could potentially
treat or prevent physical abnormalities using gene
therapy