Lectureoneia
- 1. Lecture 1 General med_2nd semester Introduction. The object and significance of histology. Short history of the line. Brno histological and embryological school. Methods used to study of cells and tissues Cytology: The cell - definition and general characteristics. Cell membrane, cell surfaces and intercellular junctions. Cell nucleus - its structure and function. Chromosomes
- 3. 2008 ISBN: 978-1-4160-3706-4 The Developing Human, 8th Edition - Clinically Oriented Embryology With STUDENT CONSULT Online Access By Keith L. Moore, BA, MSc, PhD, FIAC, FRSM and T. V. N. Persaud, MD, PhD, DSc, FRC Path(Lond) 536 pages 1805 ills Trim size 8 1/2 X 10 7/8 in $69.95, Softcover
- 4. 2008 ISBN: 978-1-4160-3705-7 Before We Are Born, 7th Edition - Essentials of Embryology and Birth Defects With STUDENT CONSULT Online Access By Keith L. Moore, BA, MSc, PhD, FIAC, FRSM and T. V. N. Persaud, MD, PhD, DSc, FRC Path(Lond) 368 pages 1308 ills ($54.95, Softcover)
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- 6. The object and significance of histology and embryology Short history of the line Brno histological and embryological school Methods used to study of cells and tissues
- 7. histology and embryology= fundamental branches on medical schools greek 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 of microscopic parameters of animal and plant tissues recently, histology = as a branch of science that treats microscopic and submicroscopic structure (organization) of animal or plant bodies on medical schools - the microscopic and submicroscopic structure of human body
- 8. animal and plant organisms consist of organs, organs of one or more tissues and tissues are composed of cells that are considered for elementary units of the living substance in accordance with 3 mentioned structural levels – cells, tissues, and organs – histology is classified 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 organs major interdisciplinary branches: histochemistry, histophysiology, pathological histology, and electron microscopy Exploration 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. embryology – its aim and orientation are quite different the term - of greek words en = in, bryein = to swell embryology deals with study of individual development of organisms individual development /ontogenetic development = ontogeny/ starts with fertilization of the ovum and ends by death of respective individual the main reason why histology and embryology are teached together is that all multicellular organisms begin their existence as single cells = generative cells or gametes model of simultaneous teaching of both disciplines is often in countries of middle Europe
- 10. History of the line development of histology as a separate branch of science was closely associated with fullfillment of 3 preconditions: the construction of the light microscope the proclamation of the cell theory the improving of methods of tissue processing a) beginning of microscopic examinations dates from the end of sixteenth century father Hans and his son Zacharias Jansen constructed the first simple microscope (1590) R. Hooke and M. Malpighi have employed microscope in studies of structural features of various organisms (the first half of the 17th century) A. Leeuvenhook (between 1673-1716) constructed and used composed microscope 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 century when cell nucleus and basic cell organelles (e.g. centrioles, mitochondria, apparatus of Golgi) have been discovered
- 11. b) the proclamation of the cell theory - an idea according to it the all animal similar as plant organisms consist of cells in biology the theory was introduced independently by Czech scientist J. E. Purkyně (1837) + two German microscopists M. Schleiden (1838) and T. Schwann (1839) German pathologist R. Virchow (1863) postulated - cells arise only through mitotic division of pre-existing cells c) to introduce adequate methods of tissue processing for the light microscopic examinations - first commercially used microtomes occur during the second half of the 19th century, - new fixation and embedding media are proved, - new histological dyes originally prepared for staining of textiles are explored in stainig of cells and tissues
- 12. History of histology and embryology in Brno the Department of Histology and Embryology was established in 1919 three 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. 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. The preparation of tissues and organs for microscopic examination two 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. Observation of dead tissues or organs is standardly used in histology it has a great advantage - specimens are permanent and may be stored for years tissue 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 sections making of permanent preparations will be described and demonstrated in practice
- 16. CYTOLOGY Definition of cell: an elementary unit of living substance that is capable basic vital functions (metabolism, autoreproduction, growth, movement etc.) 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. Shape, size, and life-time of cells variable 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. Eukaryotic cell as a system animal cell, isolated or within tissue, shows high level of organization and may be compared to an opened system it exchanges substances, energy and informations with its enviroment organization of the system is maintained in the stationary status because all processes in living cells are directed to a permanent rebuilding and establishing of the balance between them and environment the 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 form supramolecular complexes - ribosomes, membranes, microtubules cell organelles - mitochondriae, Golgi apparatus, centriol, endoplasmic reticulum etc. complex of cell organelles + nucleus + plasmalemma = a cell cell components observable with the light microscope: have been already described in the second half of the 19th century important progress in study of cell components has come with an introduction of electron microscopy in cytology
- 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 components the cytoplasm - is concentrated around the nucleus and is the site of metabolic and synthetic activities of each cell the 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 environment the nucleus and cytoplasm differ from each other not only in their physical and chemical properties but also in their structural organization and function up to date accepted structural organization of both cell compartments in the fixed cell is based on the use of the electron microscope Structural components of the fixed animal cell the nucleus: - nuclear envelope - chromatin - nucleolus - nuclear cytoskeleton (- nuclear inclusions)
- 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. the cell membrane (plasma membrane, plasmalemma) – separates cell from the environment and maintains its integrity Phospholipid bilayer.
- 22. Structure of the unit (biological) membrane membranes are the most frequent supramolecular structures found in cells apart from the plasmalemma, they separate vesicular, tubular nd other cellular configurations spaces limited by membranes constitute intracellular microcompartments that serve for segregation and concentration of substrates, products, and other substances in cellular interior the all membranes in cells display the same characteristic trilaminar structure that has lead to a concept of the unit membrane the total thickness of the unit membrane is about 7.5 to 10 nm
- 23. unit membrane consists of two electron-dense layers (about 2.0 thick) separated by 3.0 nm thick intermediate light layer the intermediate or central lucent layer is formed of bimolecular layer of lipids with hydrophilic ends of lipids proteins are associated - they form peripheral dense layers - peripheral proteins integral or penetrating proteins
- 24. the arrangement of lipids and proteins in the unit membrane is very dynamic and is in permanent renewal during the cell life-time fluid mosaic model of the membrane unit many intracellular compartments are fabricated of unit membranes (Golgi apparatus, endoplasmic reticulum, wall of the mitochondrion, nuclear envelope etc).
- 25. The plasma membrane and its specializations The plasma membrane (cell membrane) a thin limiting membrane that surrounds cell body against the external environment plasma membrane is not detectable by the light microscope as viewed with the electron microscope, the plasma membrane is only 8 to 10 nm thick and shows trilaminar structure of the unit membrane in many cells, a surface coat composed of protein-polysaccharides covers the outer membrane surface = glycocalix functions 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. Glycocalix visualized using the ruthenium red staining on apices of nonciliated and ciliated cells in the oviduct
- 27. Specializations of the cell surface in 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 lamina the 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. Pinocytosis (cell drinking) is a way of the internalization of colloid fluids surrounding the cell the process begins by the binding of colloid molecules to the cell membrane, after binding the respective membrane parts form small pits or caveolae that then pinch off and give to rise pinocytotic vesicles they contain internalized colloid molecules and then pass through the cytoplasm to reach the opposite cell aspect where they fuse with the plasma membrane and release their fluid content exocytosis = release of content of pinocytotic vesicles Phagocytosis
- 29. Lateral cell aspects: may be smooth (rarely) but may also form more or less extensive interdigitations intercellular space = 10 to 20 nm wide separates plasma membranes of adjacent cells Basal cell aspect – smooth or in cells specialized for transport of ions it is organized in basolateral labyrinth
- 30. Intercellular junctions are local specializations of lateral cell membranes between adjacent cells in 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 junctions Adhering 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
- 32. Spot desmosome (macula adherens) occurs especially in tissues that are subjected to extreme mechanical stress about 0.1 um in diameter intercellular space is 30 nm wide and contains extracellular glycoproteins that promote adhesion of adjacent cells on 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
- 33. Spot desmosomes
- 34. Belt desmosome (zonula adherens) encircles an epithelial cell completely (zone zonula) in addition, the intercellular space is about half as wide (15 nm) cytoplasmic plaques are poorly develop hemidesmosomes = junctions between the plasmalema of basal aspect and lamina basalis spot-like appearance
- 35. Occluding junction = sites where plasma membranes are in such close contact that their integral and peripheral proteins are fused integral proteins that are shared belong to family occludins and claudins are called also tight junctions or zonulae occludentes because they have belt-like structure and encircle epithelial cell completely in a manner similar to that of the belt desmosome the function of tight junction is to seal the extracellular space between adjacent epithelial cells they prevent fluid penetration they also determine the apical and basolateral domains in cells
- 36. Communicating junction or gap junction occur between a variety of excitable and non-excitable cells; serve to passage of ions and electrical impulses in the cardiac and smooth muscle they usually show form of plaques or spot-like regions (0.5 to 1.0 um in d.) in which membranes of adjacent cells run in close apposition intercellular 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
- 37. CELL NUCLEUS AND NUCLEOLUS – STRUCTURE AND FUNCTION CHROMOSOMES the nucleus is the center of cellular activity, containing chromosomal DNA and systems for synthesis and processing that allow the information in the DNA to be expressed as specific proteins in the cytoplasm with other words said THE NUCLEUS PLAYS AN IMPORTANT ROLE IN GENE EXPRESSION, HEREDITY, AND CELL DIVISION - the nucleus of dividing cell - the nucleus of interphase (not dividing) cell