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Kharkov National Medical University. Department of Histology, cytology and embryology. HISTOLOGY. studies microscopic structure and function of the human organism. The Cell. The Cell. is the structural and functional unit of the organism. Structure of a typical cell. Cell membrane
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Kharkov National Medical University Department of Histology, cytology and embryology
HISTOLOGY studies microscopic structure and function of the human organism
The Cell is the structural and functional unit of the organism
Structure of a typical cell • Cell membrane • Nucleus • Cytoplasm non-membranous organelles cytosol membranous organelles
Biological Membrane is a structural unit of a cell Biological membrane in the cell membrane, nucleus and some organelles
Non-membranous Organelles • 1. Cytoskeleton is the system of microtubules
2. Cell center 2 centrioles – consist of 9 triplets of microtubules. Formation of mitotic spindle
3. Ribosomes two subunits - synthesize proteins; Fixed on RER, or free ribosomes
1. Mitochondrion (two membranes) - synthesis of energy - ATP
2. Endoplasmic reticulum(net of membranes)smooth (SER) & rough (RER) RER contains ribosomes SER Function: Synthesis Storage Transport SER - of lipids and carbohydrates RER - of proteins
Packaging of proteins, formation of lysosomes, secretion, 3. Golgi Apparatus formation of compound molecules – glycoproteins, lipoproteins
4. Lysosome is digestive apparatus, contains enzymes(autolysis)
has channel proteins Intercellular Junctions 1) Gap Junction
Interlocking proteins 2) Tight Junctions
STRONG BOND Found in superficial layers of skin 3) Desmosomes
INCLUSIONS are nonliving components of a cell like: secretory granules, pigment, lipid, glycogen
Cell Cycle The life of a somatic cell is a cyclic process - cell cycle consists of two periods: interphase and mitosis. interphase contains G 1, S, G 2 stages
CELL CYCLE: Stages G1 S G2 M G1 Go Gap 1 growth, function DNA Synthesis (for new cells) stem or for differentiation Gap 2 formation of m.spindle, energy Mitosis Gap 1 for a new cycle
Mitosis Mitosis is the process of somatic cells division. Mitosis consists of : prophase, metaphase, anaphase, telophase.
Prophase Chromosomes become more coiled and visible the nuclear membrane breaks down Microtubules of centrioles form a spindle of division. Ch
Metaphase - chromosomes move to the center of the celland form the equatorial plate Ch
Anaphase - the chromosomes separate and move to opposite poles of the cell Ch
Telophase - two daughter nuclei are formed. the chromosomes uncoiledand become indistinct.
EMBRYOGENESIS IS FORMATION OF THE HUMAN ORGANISM
Week 1 • 1.Fertilization – is the fusion of the sperm and ovum = Zygote formation • 2.Cleavage – is the division of the zygote in the uterine tube = Blastula formation
Week 1 3-5 cells stage Cleavage 2 cells stage Morula Blastula . uterus . uterine tube Implantation Day 6 - 8 zygote Fertilization
Inner Cell Mass (embryoblast) Trophoblast At the end of cleavage outer cells (trophoblast) involve nutritive fluid, which forms cavity, moving inner cells (embryoblast). Blastula is formed.
Week 2. 3.Early Gastrulation (division and movement of cells).At the beginning of gastrulation (6,7 day) germ sinks into the uterine wall – implantation.Gastrulation leads to formation of three germ layers –ectoderm, endoderm andmesodermand extraembryonic organs: amnion, yolk sac chorion
Week 2 chorion Extraembryonic Mesoderm of Amnion and Yolk Sac Ectoderm amnion Endoderm yolk sac
Gastrulation is finished with the formation of axial organs –neural tube, notochord, somites (mesoderm),locating betweenectoderm and endoderm. From them develop tissues and organs! Neural tube Somate amnion ectoderm endoderm yolk sac Notochord
Body flexion formation(Gut formation. Gut is the upper part of yolk sac) longitudinally transversely gut head right left
Differentiation of germ layers and axial organs • What develops from them?
Surface Ectodermdifferentiates to skin, oral, rectal epithelium, corneal epithelium, tooth enamel amnionectoderm stomatodeum
Endodermdifferentiates toepithelium of stomach, intestine, liver, pancreas, respiratory, endocrine system -- 3-4 weeks - gut endoderm gut
Extra mesoderm- formation of the first blood vessels in the wall of yolk sac and allantois blood vessels
dermatome - dermis of skin myotome - muscles, sclerotome - skeleton, except skull, Body Mesoderm 1. Somite urogenital system including kedneys, gonads, ducts, and accessory glands 3. Intermediate Mesoderm. Nephrotome 2. Lateral Mesoderm - serous membranes of pleura, pericardium and peritoneum 4. Mesenchyme (loose part) – connective tissue of viscera and limbs, blood and lymph cells, vessels, smooth muscle
Late embryonic stages • Histogenesis • Organogenesis