Histology Revision 2 2024 PDF

Medicine and Surgery Program Fall 2023-2024 NORMAL STRUCTURE Prof. dr. Manal shaaban Hafez OF HUMAN BODY Professors of Histology and Cell Biology MODULE Dr. Asmaa El shafei Lecturer of Histology and Cell biology Course C...

Medicine and Surgery Program Fall 2023-2024 NORMAL STRUCTURE Prof. dr. Manal shaaban Hafez OF HUMAN BODY Professors of Histology and Cell Biology MODULE Dr. Asmaa El shafei Lecturer of Histology and Cell biology Course Code (BMS 111 ) ▪ Ectodermal, mesodermal or endodermal in origin. ▪ Continuous sheet of joined cells ( cellular attachment) with minimal intercellular space. ▪ The upper surface of cells is free, while the basal surface rests on a basement membrane. ▪ Avascular (Receives nutrition from underlying C.T. by diffusion). ▪ Innervated. ▪ High power of regeneration. C.T. 3  Types of Epithelium I- Surface II- Glandular III- Neuro- IV- Myo- epithelium epithelium epithelium epithelium Covering Lining Secretory Sensation Contraction surface cavities ✓ Covers surfaces or lines cavities. ✓ Classified according to Number of layers into: Simple Epith. Stratified Epith. One layer ˃ one layer  Definition: Single layer of flat cells with flat nuclei. Function: Provides a thin and smooth surface, allows diffusion and gas exchange Sites: 1. Blood vessels (Endothelium). 2. Serous sacs: pleura, pericardium, peritoneum (Mesothelium). 3. Lung alveoli. 1 2 3  Definition: ✓ Single layer of cubical cells with central rounded nuclei. Function: Secretion and reabsorption. Sites: It lines: 1. Follicles of thyroid gland 3 2. Tubules of kidney 2 1  Function: Cilia move fluids or Function: Secretion & absorption. particles over the epithelial surface in one direction. Sites: It lines: Sites: It lines: 1. Female genital tract; (Fallopian tube, 1. Stomach. uterus) to move ova. 2. Intestine. 2. lung bronchioles to move secretions. Cilia Definition: Single layer of crowded cells, some are tall & some are short, all cells rest on the basement membrane but some of them don't reach the surface, so the nuclei are present on different levels giving a false impression of stratification. Three types Stereocilia= long non motile Ciliated with motile cilia Non- ciliated microvilli & goblet cells  Ciliated with motile cilia Ciliated with non-motile cilia Non- ciliated (stereocilia)= long microvilli & goblet cells (Respiratory epith.) Sites: Sites: Sites: Duct of salivary glands Epididymis Upper respiratory tract (male genital system) (trachea and bronchi) Non- keratinized Types & sites Keratinized ✓ Oral cavity ✓ Esophagus ✓ Cornea ✓ Epidermis of ✓ Vagina skin  ✓ Number of layers are changeable according to state of organ, Resting on non-clear & non-wavy B.M. ▪ Basal layer: ✓ Single layer of cuboidal cells with central rounded nuclei. ▪ Intermediate layer: ✓ Multiple layers of polyhedral cells with central rounded nuclei. ✓ Cells can glide & change the number of layers. ▪ Superficial layer: ✓ Dome-shaped cells. ✓ Some of its cells are binucleated. ✓ They are covered by plaques for protection against the cytotoxic effect of urine.  Function: Protection & distensibility. Site: Urinary tract (Uroepithelium): Urinary bladder & ureter. ❑ In Empty bladder: Formed of 6-8 layers & superficial cells are dome-shaped. ❑ In Full bladder: Formed of fewer layers (2-3) & superficial cells become flattened.  Definition: Type of epithelium modified to form secretion in the glands. According to presence or absence of ducts Exocrine gl. Mixed gl. Endocrine gl. Formed of Formed of Contain both Secretory cells & ducts. Secretory cells & bl. vessels. endocrine & exocrine parts. Secrete mostly hormones.  1. According to Number of cells Unicellular gland Multicellular gland One cell e.g. Goblet cell Multiple cells e.g. Salivary glands  2. According to Type of secretion Serous gl. Mucous gl. Mucoserous gl. Watery secretion with Mucous secretion e.g. Both mucous & serous secretion enzymes e.g. Parotid gl. Goblet cell, Sublingual gl. e.g. Submandibular gl. 16  3. According to Mechanism of secretion Merocrine Apocrine Holocrine : By exocytosis. No changes Secretion come out with apex The whole cell comes out with in cells eg. Salivary gl. of cells. eg. Mammary gl. secretion. eg. Sebaceous gl.  Definition: Special type of Definition: Special type of epithelium epithelium modified to contract. modified to act as receptors, formed of Branched cells, their cytoplasm contain sensory & supporting cells. contractile filaments (actin &myosin) The base of sensory cells are surrounded with and intermediate filaments sensory nerve fibers to conduct stimuli. Site: Surround secretory portions of Sites: glands, to squeeze them and eject 1. Taste buds of tongue. secretion into ducts e.g. salivary & 2. Organ of Corti of ear. mammary gls.  Definition: asymmetrical distribution of: ✓ Organelles and , ✓ Membrane proteins within the cell. ✓ Apical surface ( free surface): is directed toward the exterior surface or the lumen of an enclosed cavity or tube. ✓ Lateral surface: communicates with adjacent cells and is characterized by specialized attachment areas. ✓ Basal pole (basal surface): rests on the basal lamina anchoring the cell to underlying connective tissue.  Junctions Lateral surface Lateral inter-digitation Basement membrane Specialization of Basal Epithelial cell surfaces Basal infoldings surface (Modifications) Hemidesmosome Microvilli Apical surface Cilia & Flagella Stereocilia  Cell junctions Adhering junctions Tight junction Gap junction 1.Zonula adherence 2. Macula adherence Encircles the epithelial cells (Belt) single spot Zonula Occludens  Occluding (tight ) Adhering (anchoring) Communicating (gap) junctions junctions junctions Intercellular Cell membrane of Cell membranes of Membrane proteins space both cells fuse both cells come in form channels Together close contact with a between adjacent Closed IC space. minimal IC space cells Transmembrane Occludins Cadherins Connexins protein Filaments thin filaments Intermediate ----------------- filaments Function Barriers and Strong cellular Communication and Trans-cellular attachment transmission of ions, transport nerve impulses and small molecules 22  epithelium ▪ Made up of widely separated different type of cells. ▪ Supported by abundant extracellular matrix (ECM). ▪ Contains connective tissue fibers. ▪ Penetrated by blood vessels, lymphatics and nerves. ▪ Mesodermal in origin. C.T. 23 ▪ Made up of widely separated different type of cells. ▪ Supported by abundant extracellular matrix (ECM). ▪ Contains connective tissue fibers. ▪ Penetrated by blood vessels, lymphatics and nerves. ▪ Mesodermal in origin. epithelium C.T. 24 1 2 3  3 types of Fibers Collagen Elastic Reticular  Structure: formed of collagen protein. Synthesis: mainly by Fibroblasts. (Chondroblasts, osteoblasts & odontoblasts). LM: The most common fibers in connective tissue ✓ Forming strong wavy bundles formed of non- branching fibers. ✓ Pink with eosin (acidophilic fibers) Character: ✓ Strong and tough fiber. ✓ Un-stretchable fibers. ✓ Un-elastic. ✓ Boiling forms gelatin Functions: ✓ Gives strength and resist stretching. ✓ Forming all tendons.  Structure: formed of elastin protein. Synthesis: Fibroblasts (Chondroblasts & smooth ms) LM: Rubber like fibers ✓ Individual thin & long and branching fibers. ✓ Faintly acidophilic, brown with Orcein Character: ✓ Stretchable and recoil fibers. Functions: ✓ Gives elasticity. Sites: Wall of large blood vessels (Aorta) forming elastic laminae. Lung , elastic ligaments of the vertebral column. Aorta  Structure: Formed mainly of collagen type III+ carbohydrate (PAS positive). Synthesis: Fibroblasts & Reticular cells. LM: ✓ Thin, short and branching (anastomosing) fibers forming delicate fibrillar network. ✓ Invisible with eosin, dark brown with silver. Character: ✓ Loose flexible network. Functions: ✓ They form supportive network (Stroma) in different organs & glands. Sites: Bone marrow, spleen, lymph node and liver.  Free transient cells and Fixed cells and are are derived from derived from UMCs haemopoietic stem cells  Origin: UMC. Site: Around blood capillaries. LM: (as UMC) EM: (as UMC) + Actin and myosin filaments. Functions: Adult mesenchymal stem cell. ✓ In case of injury, it can differentiate into: 1. Other types of C.T. cells. 2. Smooth muscle cells. 3. Endothelial cells. ✓ Vasoconstriction of capillaries.  Fibroblast Fibrocyte (Young, Immature) (Old, Mature) EM ✓ Well-developed RER. ✓ Few organelles. ✓ Well-developed Golgi complex. ✓ Many mitochondria. ✓ Euchromatic nucleus. ✓ Heterochromatic nucleus.  Unilocular Adipocyte Multilocular Adipocyte LM ✓ Large and oval. ✓ Smaller and rounded ✓ Single giant fat droplet. ✓ Multiple small droplets. (Signet ring appearance) by H&E ✓ Peripheral flat nucleus ✓ Eccentric rounded nucleus ✓ Stains orange with Sudan III. ✓ Stains orange with Sudan III.  Unilocular Adipocyte Multilocular Adipocyte EM ✓ Abundant SER. ✓ Less developed SER. ✓ Few mitochondria. ✓ Many mitochondria. ✓ Single large electron dense fat droplet. ✓ Multiple electron dense fat droplets. Function ✓ Synthesis and storage of fat. ✓ Thermogenesis by action of ✓ Organ support. thermogenin on fat. ✓ Heat insulation. ✓ Endocrine function: leptin increases metabolic rate and decrease food intake.  Origin: blood monocyte. LM: ✓ Large irregular cell (Pseudopodia). ✓ Basophilic granular cytoplasm. ✓ Eccentric dark kidney- shaped nucleus. ✓ Vital stains: (Indian ink). EM: ✓ Rich in lysosomes & Prominent Golgi. Functions: Phagocytic activity. 1. Form multinucleated foreign body giant cells. 2. Antigen presenting cell (APC). 3. Destruction of old RBCs in liver & spleen.  Origin: UMCs in bone marrow. Site: Perivascular and mucosal (under epith.). LM: ✓ Large cell. ✓ Granular, dark basophilic cytoplasm. ✓ Central rounded pale nucleus. ✓ Metachromatic stained with Toluidine blue (Change the color of basic dyes from blue to purple). EM: ✓ Well developed rER, Golgi & many mitochondria. ✓ Numerous dense secretory granules in the cytoplasm. ✓ Euchromatic nucleus.  Origin: B-lymphocyte. Site: lymphoid tissue. LM: ✓ Large oval cell. ✓ Deep basophilic cytoplasm (negative Golgi Image). ✓ Eccentric rounded nucleus (Cart-wheel/clock-face). EM: ✓ Well developed rER, Golgi & many mitochondria. ✓ heterochromatic nucleus. ✓ NO secretory granules in the cytoplasm. Fuctions: Immunological role: Production of antibodies.  Classification is based on the: - Proportion of cells to matrix. - Arrangement & types of fibers. Embryonic C.T. C.T. proper Specialized C.T. 1. Mesenchymal C.T. 1. Loose areolar C.T. 1. Cartilage 2. Mucoid C.T. 2. Dense C.T. 2. Bone 3. Elastic C.T. 3. Blood 4. Reticular C.T. 5. Adipose C.T. 38 Structure:- More cellular, More vascular & less fibrous Cells: All cells especially fibroblasts & macrophages. Fibers: All fibers (3 types). Ground substance: Abundant. Contains potential cavities (areolae), , richly supplied with blood vs. Sites: Found everywhere except in the brain. Around organs, blood vessels & nerves. Under epithelium; in submucosa & dermis of skin. Functions Pulp of teeth 1. Support & binds tissues. 2. Nutrition. 3. Filling space between fibers of muscle and nerves. 39 4. Defend against infection (by its immune cells).  Structure More fibrous, less cellular and less vascular Cells: Predominant fibroblasts. Fibers: Bundles of collagen fibers. Ground substance: minimal + few blood vs. Regular dense Types Irregular dense 40 Structure Parallel wavy collagen bundles with rows of fibroblasts in between. Sites Tendon. Ligaments. Cornea. Function Withstands stretch in one direction. 41 Structure Irregular collagen bundles with scattered fibroblasts in between. Sites Organ capsules. Dermis of skin. Sclera. Function Withstands stretch in different directions. 42  White adipose C.T. Brown adipose C.T. Structure ✓ Unilocular fat cells. ✓ Multilocular fat cells. ✓ It is the primary site for ✓ Brown pigmented due to: storage of energy (in the ▪ Rich Blood supply form of triglycerides) and ▪ Abundant Mitochondria has a rich nervous supply. contain cytochrome oxidase ✓ Insulin hormone assist in the pigment control of lipid storage in adipose tissue.  White adipose C.T. Brown adipose C.T. Sites Under the skin. Fetus and newborn: axilla & Around kidney. interscapular. Mammary gland. Adult: around thoracic aorta. Functions ✓ Storage of fat. ✓ Thermogenesis by action of ✓ Support soft organs as kidney. thermogenin on fat; ✓ Heat insulation. Trans-membrane protein in ✓ Forms body contours esp. in mitochondria, causes release of females protons away from ATP synthesis ✓ Endocrine function: leptin resulting in heat production. increases metabolic rate and decrease food intake (Regulate appetite) Thank You 45