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  1. 1. Lecture 1 General med_2nd semesterIntroduction. The object and significance of histology. Short history of the line. Brno histological and embryological school. Methods used to study of cells and tissuesCytology: The cell - definition and general characteristics. Cell membrane, cell surfaces and intercellular junctions. Cell nucleus - its structure and function. Chromosomes
  2. 2. Textbooksrecommended tostudy:
  3. 3. 2008ISBN: 978-1-4160-3706-4The Developing Human, 8th Edition - Clinically Oriented Embryology WithSTUDENT CONSULT Online AccessBy Keith L. Moore, BA, MSc, PhD, FIAC, FRSM and T. V. N. Persaud, MD, PhD, DSc,FRC Path(Lond)536 pages 1805 illsTrim size 8 1/2 X 10 7/8 in$69.95, Softcover
  4. 4. 2008ISBN: 978-1-4160-3705-7Before We Are Born,7th Edition - Essentialsof Embryology and Birth DefectsWith STUDENT CONSULT OnlineAccessBy Keith L. Moore, BA, MSc,PhD, FIAC, FRSM and T. V. N.Persaud, MD, PhD, DSc, FRCPath(Lond)368 pages 1308 ills($54.95, Softcover)
  5. 5. UKB, Kamenice 5, Building A9 A, 625 00 BrnoPhone: 549 493 619Mobile: 608 877 315http://www.lekarskeknihy.cz After your order we will contact you when the books are available to you at our bookshop. Notice that terms of delivery of some books are about one month. We prefer payment in CZK cash. Another method of payment is possible only after individual deal.
  6. 6. The object and significance ofhistology and embryologyShort history of the lineBrno histological and embryologicalschoolMethods used to study of cells andtissues
  7. 7. histology and embryology= fundamental branches on medicalschoolsgreek histos meaning "tissue„ + logos meaning "the study off" (knowledge or science)the term was primarily used in strict sense of the word as a denotation for the study ofmicroscopic parameters of animal and plant tissuesrecently, histology = as a branch of science that treats microscopic andsubmicroscopic structure (organization) of animal or plant bodieson medical schools - the microscopic and submicroscopic structure of human body
  8. 8. animal and plant organisms consist of organs, organs of one or more tissues and tissues arecomposed of cells that are considered for elementary units of the living substancein accordance with 3 mentioned structural levels – cells, tissues, and organs – histology isclassified into 3 sections: cytology - deals with structural and ultrastructural organization of cells histology proper (or histology in strict sense of this word) - describes the structure and function of tissues microscopic anatomy - a section of branch studying microscopic and fine structure of individual organsmajor interdisciplinary branches:histochemistry, histophysiology, pathological histology, and electron microscopyExploration of histology: a basic subject, on which pathology a pathophysiology are built in diagnosis of diseases (department of pathology) in farmaceutical industry for testing drugs and artificial materials used for substitutions of natural organs in control of food quality
  9. 9. embryology – its aim and orientation are quite differentthe term - of greek words en = in, bryein = to swellembryology deals with study of individual developmentof organismsindividual development /ontogenetic development = ontogeny/starts with fertilization of the ovum and ends by death of respectiveindividualthe main reason why histology and embryology are teached together is thatall multicellular organisms begin their existence as single cells =generative cells or gametesmodel of simultaneous teaching of both disciplines is often in countries ofmiddle Europe
  10. 10. History of the linedevelopment of histology as a separate branch of science was closely associatedwith fullfillment of 3 preconditions: the construction of the light microscope the proclamation of the cell theory the improving of methods of tissue processinga) beginning of microscopic examinations dates from the end of sixteenth centuryfather Hans and his son Zacharias Jansen constructed the first simple microscope(1590)R. Hooke and M. Malpighi have employed microscope in studies of structuralfeatures of various organisms (the first half of the 17th century)A. Leeuvenhook (between 1673-1716) constructed and used composedmicroscope and published a series of observation upon protozoa, bacteria, muscle,nerve and other structures (the second half of the 17th century)great boom of light microscopy comes in the 19th centurywhen cell nucleus and basic cell organelles (e.g. centrioles, mitochondria, apparatusof Golgi) have been discovered
  11. 11. b) the proclamation of the cell theory - an idea according to itthe all animal similar as plant organisms consist of cellsin biology the theory was introduced independently by Czech scientistJ. E. Purkyně (1837)+two German microscopists M. Schleiden (1838) and T. Schwann (1839)German pathologist R. Virchow (1863) postulated - cells arise only throughmitotic division of pre-existing cellsc) to introduce adequate methods of tissue processing for the lightmicroscopic examinations- first commercially used microtomes occur during the second half of the 19thcentury,- new fixation and embedding media are proved,- new histological dyes originally prepared for staining of textiles areexplored in stainig of cells and tissues
  12. 12. History of histology and embryology in Brnothe Department of Histology and Embryology was established in 1919three teachers and scientists achieved international reputation Prof. MUDr. František Karel Studnička (1870 - 1955) is founder of department and first head, he became famous in Europe through the exoplasmic theory: the all-intercellular substances are living and arise as a result of transformation of cell processes, he prepared and published the first czech handbook of microscopy (Praktická mikroskopie, 1923) Prof. MUDr. Jan Florian (1897 - 1942) pupil of Studnička Florian was outstanding embryologist in the world literature he has firstly described very young human embryos aged only 13 to 15 days his observations are valid to recent time
  13. 13. Prof. MUDr. Karel Mazanec, DrSc. (1922 - 1967) embryologist and electron microscopist he introduced TEM - 60 years of the last century he explored TEM in study of preimplantation embryos of mammals author of book dealing with development of the human from the zygote to the end of the 3rd week (published in German language-1953)
  14. 14. The preparation of tissues and organs for microscopic examinationtwo ways are used: - samples or specimens prepared from living cells and tissues - samples or specimens taken of dead organisms (fixed samples)Observation of living cells or tissues is very valuable as structure and function of cells may be studied simultaneously is mainly used in unicellular organisms and, occasionally, in free cells of a complex organism, preparations are not stable - CELL AND ORGAN CULTURE - cells or fragments of tissue are removed aseptically, transferred to a physiological medium and kept at a temperature normal for animal from which the sample was taken. The cultures are placed in thin glass vessels or in hanging drops on a coverglas mounted over a hollow slide - VITAL AND SUPRAVITAL STAINING - in vital staining, dyes are injected into the living animal. The activity of certain cells will result in the selective absorption of the coloring material by these cells. An example of this procedure is the staining by trypan blue of macrophages on the basis of their ability to phagocytose foreign particles. In supravital staining, a dyestuff is added to a medium of cells already removed from the organism. Examples of this technique are the staining of mitochondria in living cells by Janus green, of lysosomes by neutral red and of nerve fibers and cells by methylene blue.
  15. 15. Observation of dead tissues or organsis standardly used in histologyit has a great advantage - specimens are permanent and may be stored foryearstissue processing involves 6 phases: sampling (taking or obtaining) of tissue probes fixation of samples embedding of samples cutting of blocks and affixing of sections staining of sections mounting of sectionsmaking of permanent preparations will be described and demonstratedin practice
  16. 16. CYTOLOGYDefinition of cell: an elementary unit of living substance that is capablebasic vital functions (metabolism, autoreproduction, growth, movementetc.) minimal unit prokaryotic cells - small - 1- 5 mm (bacteria, actinomycets), the consist of a cell wall, hyaloplasm with plasmids and ribosomes, have no nucleus and membranous organelles, DNA is not separated from other cellular components eukaryotic cells - form bodies of plants and animals, are larger and show complicated organization, contain distict nucleus surrounded with nuclear envelope, DNA is associated with histones, cells utilize membranes as main material for construction of compartments cells differ in size, shape, number (in multicellular organisms), and life-time
  17. 17. Shape, size, and life-time of cellsvariable shape of cells - environment (free cells vs tissues) and function size of cells - between 10 - 30 mm life time of cells - hours … years number of cells – 1013 -1014
  18. 18. Eukaryotic cell as a systemanimal cell, isolated or within tissue, shows high level of organization and may be compared toan opened systemit exchanges substances, energy and informations with its enviromentorganization of the system is maintained in the stationary status because all processes in livingcells are directed to a permanent rebuilding and establishing of the balance between themand environmentthe middle sized eukaryotic cell consists of molecular units of two kinds:- macromolecules (of nucleic acids, proteins, lipids, and carbohydrates) - more than 4200 milliards in average- molecules of inorganic elements (Na, K, Cl, Ca, Mg) + and molecules of water (about 225 billions in average)molecules associate each other to formsupramolecular complexes - ribosomes, membranes, microtubulescell organelles - mitochondriae, Golgi apparatus, centriol, endoplasmic reticulum etc.complex of cell organelles + nucleus + plasmalemma = a cellcell components observable with the light microscope: have been already described in thesecond half of the 19th centuryimportant progress in study of cell components has come with an introduction of electronmicroscopy in cytology
  19. 19. eukaryotic cell consists of:the nucleus - is the center of cellular activity that plays important role in gene expression, heredity and cell division. The nucleus consists of several componentsthe cytoplasm - is concentrated around the nucleus and is the site of metabolic and synthetic activities of each cellthe cell membrane - plasma membrane, plasmalemma - separates the cell from its environment and maintains its integrity, the membrane is also engaged in creation of the interior cellular environmentthe nucleus and cytoplasm differ from each other not only in their physical and chemicalproperties but also in their structural organization and functionup to date accepted structural organization of both cell compartments in the fixed cell is basedon the use of the electron microscope Structural components of the fixed animal cell the nucleus: - nuclear envelope - chromatin - nucleolus - nuclear cytoskeleton (- nuclear inclusions)
  20. 20. the cytoplasm: - cell organelles - are the "little organs" of the cell that posses a distinctive structure and well established function; they are present in most cells in different number - mitochondria, - endoplasmic reticulum - ribosomes - Golgi apparatus - lysosomes - peroxisosomes - centrioles - cell inclusions - are lifeless and have temporary character; in most cases they are of a result of the cell activity -stored foods (proteins, lipids and carbohydrates), -crystals, -pigments -secretion granules - hyaloplasm or cytoplasmic ground substance (cytosol) – it is defined as a portion of the cytoplasm that surrounds the cells organelles and inclusions it seems to be structureless, by electron microscopy and special immunohistochemical methods very fine network within it can be visualized – the cytoskeleton
  21. 21. the cell membrane(plasma membrane,plasmalemma) –separates cell from theenvironment andmaintains its integrityPhospholipid bilayer.
  22. 22. Structure of the unit (biological) membranemembranes are the most frequent supramolecular structuresfound in cellsapart from the plasmalemma, they separate vesicular, tubularnd other cellular configurationsspaces limited by membranes constitute intracellularmicrocompartments that serve for segregation and concentrationof substrates, products, and other substancesin cellular interiorthe all membranes in cells display the same characteristictrilaminar structure that has lead toa concept of the unit membranethe total thickness of the unit membrane is about 7.5 to 10 nm
  23. 23. unit membrane consists oftwo electron-dense layers (about 2.0 thick) separated by3.0 nm thick intermediate light layerthe intermediate or central lucent layer is formed of bimolecular layer of lipidswith hydrophilic ends of lipids proteins are associated - they form peripheral denselayers - peripheral proteinsintegral or penetrating proteins
  24. 24. the arrangement of lipids and proteins in the unit membrane is very dynamic and is inpermanent renewal during the cell life-time fluid mosaic model of the membrane unitmany intracellular compartments are fabricated of unit membranes (Golgi apparatus,endoplasmic reticulum, wall of the mitochondrion, nuclear envelope etc).
  25. 25. The plasma membrane and its specializationsThe plasma membrane (cell membrane) a thin limiting membrane that surrounds cell body against the external environmentplasma membrane is not detectable by the light microscopeas viewed with the electron microscope, the plasma membrane is only 8to 10 nm thick and shows trilaminar structure of the unit membranein many cells, a surface coatcomposed of protein-polysaccharidescovers the outer membrane surface= glycocalixfunctions of the glycocalix: stabilizes the cell membrane participates in cell adhesion is responsible for antigenic properties of the cell is also engaged in processes of cell recognizing
  26. 26. Glycocalix visualized using the ruthenium red staining onapices of nonciliated and ciliated cells in the oviduct
  27. 27. Specializations of the cell surfacein cells, namely polarized epithelial ones, three distinct aspects of the plasma membrane are distinguished: - an apical cell surface - it borders a luminal space - a lateral cell surface - is oriented to the adjacent cell - a basal cell surface - it is in contact with the basal laminathe apical cell surface - may be smooth or is provided with microvilli, cilia(rarely flagellum), in addition, it is often involved in processes of cell internalization- e.g. cell drinking or pinocytosis and phagocytosis
  28. 28. Pinocytosis (cell drinking)is a way of the internalization of colloid fluids surrounding the cellthe process begins by the binding of colloid molecules to the cell membrane,after binding the respective membrane parts form small pits or caveolae that thenpinch off and give to rise pinocytotic vesiclesthey contain internalized colloid molecules and then pass through the cytoplasm toreach the opposite cell aspect where they fuse with the plasma membrane and releasetheir fluid content exocytosis = release of content of pinocytotic vesicles Phagocytosis
  29. 29. Lateral cell aspects: may be smooth (rarely) but may also form more or lessextensive interdigitationsintercellular space = 10 to 20 nm wide separates plasma membranes of adjacentcellsBasal cell aspect – smoothorin cells specialized for transportof ions it is organized inbasolateral labyrinth
  30. 30. Intercellular junctionsare local specializations of lateral cell membranes between adjacent cellsin general, they have three functions: increase the cellular attachment - adhering junctions seal the intercellular space - occluding junctions serve for cell-to-cell communication - gap or communicating junctionsAdhering junctions:form strong bond between adjacent cells or between basal part of the cell membrane  spot desmosome (macula adherens)  belt desmosome (zonula adherens)  hemidesmosome proteins as cadherins + desmoplakin and plakoglobin
  31. 31. Spot desmosome (macula adherens) occurs especially in tissues that aresubjected to extreme mechanical stressabout 0.1 um in diameterintercellular space is 30 nm wide and contains extracellular glycoproteins thatpromote adhesion of adjacent cellson both cytoplasmic sides of the macula adherens, there are 20 nm thick electron dense plaques (containing special proteins - desmoplakins I and II), into which tonofilaments insert
  32. 32. Spot desmosomes
  33. 33. Belt desmosome (zonula adherens)encircles an epithelial cell completely(zone zonula)in addition, the intercellular space isabout half as wide (15 nm)cytoplasmic plaques are poorly develophemidesmosomes = junctions between the plasmalema of basal aspect and laminabasalis spot-like appearance
  34. 34. Occluding junction= sites where plasma membranes are insuch close contact that their integral andperipheral proteins are fusedintegral proteins that are shared belongto family occludins and claudinsare called also tight junctions orzonulae occludentes because theyhave belt-like structure and encircleepithelial cell completely in a mannersimilar to that of the belt desmosomethe function of tight junction is to sealthe extracellular space between adjacentepithelial cellsthey prevent fluid penetrationthey also determine the apical andbasolateral domains in cells
  35. 35. Communicating junction or gap junctionoccur between a variety of excitable and non-excitable cells; serve to passageof ions and electrical impulses in the cardiac and smooth musclethey usually show form of plaques or spot-like regions (0.5 to 1.0 um in d.) in whichmembranes of adjacent cells run in close appositionintercellular space is retained and reduced to only 2 to 4 nm are numerous bridges in extent of each gap junction are formed by a special protein, called connexin
  36. 36. CELL NUCLEUS AND NUCLEOLUS – STRUCTUREAND FUNCTIONCHROMOSOMESthe nucleus is the center of cellular activity, containing chromosomalDNA and systems for synthesis and processing that allow the informationin the DNA to be expressed as specific proteins in the cytoplasmwith other words saidTHE NUCLEUS PLAYS AN IMPORTANT ROLE IN GENEEXPRESSION, HEREDITY, AND CELL DIVISION- the nucleus of dividing cell- the nucleus of interphase (not dividing) cell