Cytology PDF

Cytology  CYTOLOGY It is one of the biological sciences which study the structure, histochemistry and ultrastructure of the cell concerning the immunohistochemistry and cell genetics.  A-Cytoplasm 1-Organelles 2-Inclusi...

Cytology  CYTOLOGY It is one of the biological sciences which study the structure, histochemistry and ultrastructure of the cell concerning the immunohistochemistry and cell genetics.  A-Cytoplasm 1-Organelles 2-Inclusion 3-Other component (a) Membranous Organelles:- 1) cell membrane2) Mitochondria 3) Endoplasmic reticulum 4) lysosome 5) Golgi Apparatus (b) non membranous 1) Free ribosome.2)Cilia & flagella3) Microtubules.4) Filament & fibrils.5) centriole “centrosome” These components are Constant in the eukaryotic cell& embedded in the cytoplasm. 2-Inclusion Secretory granules Stored food Pigments a- Lipid 1) Exogenous b- Carbohydrate 2) Endogenous B-Nucleus Nuclear envelope chromatin karyolymph nucleolus 1-Cell membrane:- It also known as plasmalemma & plasma membrane (trilaminar structure) is composed of dense layer of cytoplasm surround the eukaryotic cell is composed of 2 layer of dense protein in between present phospholipids Its thickness range from 8:10 nm only can seen with E.M & appear as protein swim in a sea lipid it appears as trilaminar structure , outer and inner dark layer and middle light layer , this configuration due to→ it appear like that due to deposition of reduced osmium stain on the hydrophilic side of the cell membrane These are some “theories of the structure of cell membrane Linear theory Molecular theory Fluid mosaic theory 1-Linear Theory, as the cell membrane appear as 3 line, 2 dense bilayer Phospholipids→ hydrophilic and one light intermediate→ hydrophobic 2-Fluid Mosaic theory, globules of protein move freely through the cell membrane. They are floating & changing their position from time to time. Protein → extrinsic” peripheral” are present in one side of the lipid bilayer “outside” & closely bounded to the cytoplasmic side “has non polar bond” 3) Molecular theory: it indicates biochemical structure of the cell membrane. Phospholipids” hydrophilic head, hydrophobic tail. Protein “integral and peripheral” Carbohydrate “glycoprotein and glycolipid. Cholesterol has fixing rule that it make phospholipids backed tightly together.  Function: 1-Protective 2-Regulate transport in and out of cell or subcellular domain. 3-Allow selective receptivity and signal transduction by providing ansmembrane receptors that bind signaling molecules. 4-Allow cell recognition 5- Provides anchoring sites for cytoskeletal filaments or components of the extra-cellular matrix. This allows the cell to maintain its shape and perhaps move to distant sites. 6- Help compartmentalize subcellular domains or microdomains 7- Provide a stable site for the binding and catalysis of enzymes. 8- Regulate the fusion of the membrane with other membranes in the cell via specialized junctions) 9- provide a passageway across the membrane for certain molecules, such as in gap junctions. 10- Allow directed cell or organelle motility  2- Mitochondria:- Mitochondria" is a plural term; which is appropriate because it is not usual to find a single "mitochondrion" (which may also be referred to as a "chondriosome"). Mitochondria provide the energy a cell needs to move, divide, produce secretory products, contract - in short; they are the power centers of the cell. They are about the size of bacteria but may have different shapes depending on the cell type. One of the cytoplasmic organelles, membranous can seen with light microscope using” supra vital dye of Janus “green color” It bounded by 2 membrane separated with inter membranous space. It may be short rods, threads or granules. About 2500- 3000 in each cell & increase in cell with high metabolic action. E.M. Bounded with 2 membranes. “Outer is smooth, inner extended in ward forming crista or internal ridge which divided mitochondria into incomplete compartments. The inner membrane has mitochondrial granules or elementary particles which consist of head, neck and base. It also contains matrix granules which have binding site (diformazan granules). It also contains ribosome like particles. It also contains enzymatic granules. It also contains DNA in close ring (maternal DNA). Function:- Power house of the body. Contain many biochemical reactions. Contain enzyme of crib’s cycle.  3-Lysosome:- Membranous organelles contain hydrolytic enzyme act on pH medium (acidic). Lysosomes are tiny sacs filled with enzymes that enable the cell to utilize its nutrients and are responsible for destroying the cell after it has died. However, there are some circumstances (diseases/conditions) in which lysosome begin to 'break-down' living cells. 800 nm in diameter. It derived from Golgi complex. L.M → vesicle of basophil, eosinophil and/ neutrophil.  E.M → homogenous round vesicle bounded with thin membrane. Chemically they are lipoprotein complex, their cavity filled with hydrolytic enzyme. How lysosome are formed. The lysosome are the freshly formed secretory vesicle contain hydrolytic enzyme “ primary lysosome” It comes from r.E.R as transfer vesicle contains enzyme synthesis with ribosome of r.E.R. When they grow up in the saccules of the Golgi they bud off from the mature face of the Golgi as secretory vesicle. Secondary lysosome, when the primary lysosome phagocytosis any undesirable vesicle in the cytoplasm then called secondary lysosome. If fuse with phagocytic vesicle” “phagosome” when enzyme digest vesicle → result residual body. If fuse with torn, old cytoplasmic content “cytolysosome or autophagic vacuole”. Function:- Have active role in intracellular metabolism e.g. Carbohydrate. Have active role in phagocytosis, pinocytosis, and autophagy and autolysis. Breakdown of excessive secretory granules. Share in normal secretory activity of some cells as thyroid gland. 4-Endoplasmic Reticulum:- I-Rough ER II- Smooth ER I-Rough endoplasmic reticulum (r.E.R) Membranous organelles. An endoplasmic reticulum (ER) in a cell is a system of membranes which is the site of manufacture of proteins and lipids. The "rough" component of the term "Rough Endoplasmic Reticulum" or "RER" indicates that there are ribosomes attached to the surfaces of the endoplasmic reticulum. Three dimension network of branching & anastomosing membrane. Bounded and flatten tubules. Widen sacs like structure “Cisternae” within the meshes of the cisternae Ribosome present on the surface of the sacs gives rough appearance. L.M Appear as basophilic substance of the cytoplasm “ergastoplasm '' so it called” chromidal substance” due to similarity to chromatin of the nucleus. NB (rER+ ribosome) in Nerve cell called Nissl’s body. E.M. Parrelled stack of flatten cisternae. It continues with nuclear envelope. Ribosome gives granular appearance. Function :- Synthesis of intracellular protein Synthesis of protein that segregated & transferred to Golgi apparatus as transferred vesicle. Play role in glycogen biosynthesis. Its fluid filled channel facilitates diffusion of metabolite through the cytoplasm. II-Smooth endoplasmic reticulum (sER):- Membranous network devoid of ribosome The cisternae more tubular interconnected and communicate with r.E.R& nuclear envelope. It believed now that s.E.R derived from r.E.R after loosing attached ribosome.  Function → Biosynthesis of phospholipids & fatty acid. Resynthsis of absorbed lipid and transport it to absorptive intestinal cell. Biosynthesis of cholesterol & steroid hormones. Share in metabolism of cholesterol. Synthesis of glycogen. Drug detoxification” break down of hypnotic drugs in the liver cell. Responsible for conjugation, oxidation & methylation process to detoxify or neutralize hormone or noxious substance. Share in the contraction process of the muscles, its membrane contain enzyme for calcium pump” thus pump calcium to make contraction & bull it to make relaxation. (Microsome) It denotes as vesicle generated from fragmentation of ER during process of homogenization that preceded differential or “density gradient centrifugation” so it should never applied to intact cell  5- Golgi apparatus:- * It also known as Golgi network, Golgi apparatus * Membranous organelles consists of several number of flatten sacs or cisternae that stack together like plate of cups in several location of the The Golgi apparatus consists of a collection of vesicles and folded membranes. These are usually connected to an endoplasmic reticulum (ER) as the Golgi apparatus stores and then transports the proteins produced in the ER. *Because of its functions of strong and transporting proteins, the Golgi apparatus may be creatively thought of as the "Post Office" of the cell. The Golgi apparatus is particularly well developed in cells that produce secretions. The shape of the Golgi apparatus varies according to physiological state. Hungary→ small dense body in intestinal cell. Feeding→ increase in size. Young→ Golgi form small net like structure in the axon pole of the nerve cell. Aging → theses small net became fragmented or discrete granules. E.M. Parallel array of smooth surface membrane called flatten saccules or cisternae. These cisternae flatten peripherally “budding” it assume semi lunar configuration it has two surface Concave ( mature or trans ), it associated with secretory vesicles of various stage of condensation & maturation Convex (immature), it associated with transferred vesicle of r.E.R.  Function Concentration of protein from transferred vesicle. Synthesis of polysaccharides “ hexosamine”. Conjugation (coupling) of protein to polysaccharides “giving glycoprotein”. Concentration of various hydrolytic enzymes. Play role in exocytosis process. Form glycocalyx. It has an important role in renewal of the cell membrane.  GERL It is area near the Golgi present in certain type of cells appearance → flat fenestrated saccules with dilatation → anastomosing connecting tubules the cisternae of r.E.R “area cisternae free ribosome” may has connection with it Function may be second sort of secretory product “modification” of protein from r.E.R contain phosphates enzyme share in lysosome production Part of Golgi has the same role.  (b) Non Membranous organelles 1- Free ribosome:- Small electron dense particles 15-20 nm in size Composed of r RNA & protein (Ribosomes are particles consisting of ribonucleic acid (RNA) and protein that interpret cellular information from the nucleus and synthesize appropriate proteins as required by the cell. * Ribosomes are either attached to the endoplasmic reticulum (RER) or free in the cytoplasm as polysomes. Each ribosome consists of:- ** 2 different size subunit in case of “Ribosome” ploysome they are held together by stand of mRNA  NB The protein and rRNA of the ribosome synthesis in the nucleoli then transport to the cytoplasm to form ribosome There are two Type of ribosome: Ribosome in Eukaryotic cells. Ribosome in Prokaryotic cells chloroplast & mitochondria. Function synthesis of protein  2- Centriole “Centrosome”:- It present in all dividing cell except nerve cell and R.B.Cs. Any cell contain pair of centrosome Non membranous structure. L.M (1) Small dark body surrounded with clear dark zone (microcentrum). (3) Dark zone (dense) centrophere from which astral rays or astrosphere radiate in dividing cell. (4) 0.5 u in length and 0.2 u in diameter E.M - Each centrosome consists 2 centriole cylindrical bodies both of them perpendicular to each other. - It consists of nine triple hollow microtubules. - Each triple consists of sub fibrils a.b. c. & 2 arms one connected to adjacent fibrils & other extend at center. Function Help in cell division. Formation of motile tail of the sperm. Serve as basal body (Kinetosome) & site of origin of epithelial cilia. Cantorial structure  3- Microtubules:- Slender filament structure, 24 nm in diameter of variable length tend to be straight and may be rigid or flexible, it can’t seen with L.M. E.M:- consists of 13 rod shape component termed protofilament. They occur in most cell type especially numerous in dividing cells when it forms the mitotic spindle. Aggregation of microtubules occur in nerve cell, lens cell, in the core of flagella “sperm tail and cilia “. * Microtubules formed from Tubulin molecules. Arranged in pair “Tubulin dimmer “. The formation of microtubules start in area close to the centriole called (MTOC) → MicroTubules Organization Center.  Function (1) Form the contractile element in cilia & flagella. (2) Facilitate transport of various particle & many macromolecules through cytoplasm. (3) Play role in maintained the cell shape. (4) One of the cell cytoskeleton. (5) They support & provide the material synthesitized close to nucleus to the processes in nerve cell. (6) In mitosis “new microtubules formed & pull part of the chromosome during anasphase ‘mitotic spindle.  4- Cilia- flagella:- Only present in the free cell surface “columnar “ Diameter 0.2um and length 5-15um. EM 1- It has basal body derived from centriole. 2- Shaft → (axoneme) extend from basal body that push cell membrane over themselves. 3- Root → are anchoring extends from underneath basal body & extends to the cytoplasm. C.S in shaft:- Nine doublets & 2 single microtubules. Type of cilia:- 1-Kenocilia → motile 2-Sterocilia → non motile Flagellum It is a single cilium become developed the only cell having flagellum is the spermatozoa.  5- Filament & fibrils:- There are 3 types of filament in the body Neurofilament → in the nerve cell Myofilment → Actin “thin filament 5-6nm → Myosin “thick “10nm Tonofilament → present in st.sq. Epith where adjacent epithelial cell are connected by junctional complex. - It also densely backed & form (Terminal web). Function Muscular contraction in muscle cells. Contraction of non muscle cells. Movement of microvilli by the help of actin filament at the top of microvilli which inter lacing with myosin filament at bottom of the microvilli. (4) Retraction of blood clot by the help of actin & myosin filament in the blood platelets cause contraction of blood clot to stop bleeding. (5) Have role in cell division, they form contractile ring which encircle the cell at the contraction furrow which develops between the two future daughter cells, thus inducing it to deepen until cleavage is achieved.  Peroxisomes:- * Membrane bounded cytoplasmic organelles very similar to lysosome But:- - It contains enzymes that produce H2O2. - It contains also “catalase that split H2O2 → H2O+O2. Cytoskeleton:- - The cell cytoplasm contain cell skeleton which formed from an intricate 3 dimension network of filamentous structure. - These structure are not only maintained shape & organization of the cell but also it share in various activities as cellular movement. - It help in transport various substance with the cell and also help in cell division. They are:- (1) Microtubules (2) Intermediate filaments. (3) Micro filament. Inter connecting of thin filamentous bridge called microtrabecular lattice which link microtubules &perhaps other filamentous structure  (2) Cytoplasmic inclusion:- They are non living, Transitory present in the cell and composed mainly of accumulated metabolites or deposits of varied nature. It include:- 1-Secretory granules. 2-Stored food. 3-Pigements. 1-Secretory granules:- * Usually present in the glandular cell. * Protein or glycoprotein. 2-Stored Food:- Carbohydrate Which stored in the form of glycogen which present in large amount in liver cell and in muscle cell.  EM Alpha form → aggregation of election dense granules Large, rosette shape (liver) Beta form → single electron dense granules Small, spherical shape (muscle) PAS stain Best’s Carmine stain lipid It stored in the tissue as adipose tissue In frozen section stained with Osmium black → black ------Sudan black → black Oil red O → red ------ Sudan → red PAS Stain  Lipofuchsin ‘brown in color  3-Pigments:- Exogenous That generated out side the body then taken by the body. Lipochrome caretonied ‘ vegitable “. Dusts “by respiratory system “. Mineral “by ingestion of lead, silver. Tattoo marks by tattooing machine. (Ink of the tattoo taken by phagocyte & remain under subcutaneous tissue. Endogenous Generated inside the body from non pigmented ingredient:- (1) Hb “Hemoglobin. (2) Lipofuchsin ‘brown in color in fresh state present in heart, liver and nerve cell. (3) Melanin “responsible for dark color of skin, hair and eyes.  (3) Other Components (cytoplasmic matrix or (CYTOSOL) It is colloidal solution, composed of water, proteins, enzymes, nutrients and inorganic substance. It contains all cytoplasmic organelles and inclusions.  The structure of the nucleoplasma A A HC - Heterochromatin (electron dense granules): densely packed DNA without transcription It has 2 forms, the constitutive HC, which is never transcribed, and is usually attached to the nuclear envelope via the nuclear lamina. In contrast, facultative heterochromatin is densely packed only in a particular cell type but could also be euchromatin. EC - Euchromatin: less coiled DNA, the functional part of chromatin with intense mRNA synthesis NU - Nucleolus: contains genes for ribosomal RNA It appears as membrane boundary separated the nucleus from the cytoplasm. EM 2 concentric unit membrane “ inner and outer “ Trilaminar. - Outer studded with ribosome & continue with ER. - Inner attached to small particles of chromatin heterochromatin. - Nuclear pore present with septum for exchange of RNA between interior and exterior. Nuclear pores permit substances (such as nutrients, waste, and cellular information) to pass both into, and out of, the nucleus - Both membranes enclose perinuclear cisternae.  Heterochromatin 1. Euchromatin Known As Condensed extended or diffuse Location cells with low activity cells with high activity Shape dark clumps inside the envelope light stain strands of DNA and mRNA Action Inert in protein synthesis active in protein synthesis Position Peripheral chromatin Diffuse in the karyolymph Nucleolus associated chromatin Chromatin island  Nucleus Euchromatine Heterochromatine Nucleolus Heterochromatine Euchromatine Pattern of the nucleuplasma: heterochromatic - euchromatic euchromatic: transcriptionally active → less condensed often (but not always)is under active transcription fibroblast neuron heterochromatic: transcriptionally inactive → highly condensed is a tightly packed form of DNA there is not RNA synthesis there (fibrocytes) Special pattern in plasma cells „clockwise appearance”  nucleus: heterochromatin, euchromatin, and nucleolus Euchromatin is a lightly packed form of chromatin (DNA, RNA and protein) that is rich in gene concentration, and is often (but not always)is under active transcription, Heterochromatin is a tightly packed form of DNA there is not RNA synthesis there  Cell Cycle I→ G1 first gap II→S1 Synthesis stage * Is the period after end the mitosis In this stage strand of DNA become division & before S stage which it lasts for 8 synthesized and the complementary hour strand from the mother DAN (25 strand) * The cell after division has S III→G2 second gap chromosomes. Is the short period after (S) and before next * The cytoplasm grow for the next division mitosis * Some cell performs special function. Some cells leave the cycle, other perform *Some cell go into prolonged G, Stage or special function. get out of the cycle and then called (end cells) Some other go into the division & may return back to the cycle when need. S chromosome change to D chromosome in which two chromatid linked by centromere.