General Histology and Histotechnique (Lecture – Midterm)Histology 4. Polarized 5. Avascular but has a nerve supply 6. Separated from underlying tissue by basement membrane.Reasons to study Histology Functions: Protection - Skin act as a barrier (physical; organisms)Pathologist Absorption- interpretation of histological result - Small intestine linings- clinical aspect; interpreted findings - Inner lining of organs - absorbs nutrientsChemical Reaction- Life came as a result of chemical reaction Filtration- organic and inorganic substances - Kidney - Glomeruli – filters blood/waist from bloodMajor types of adult tissues: Epithelial Secretion Connective - Digestive enzymes Muscle - Glands – exocrine & endocrine Nervous - Sweat gland – perspirationEmbryonic Tissue Special Characteristics of epitheliaEctoderm Specialization of the free surfaces- epithelial, nervous tissue a. CiliaMesoderm - Motile- muscles & connective tissues - Found on the cells of the uterine tubes and in most respiratory passages.Endoderm- where epithelia arises from Function: - Transport materials across the ciliated surfacesEpithelial Tissues - To trap dirt; move mucous up and downFeatures:1. Uninterrupted layer of cells b. Stereocilia2. Cells attached to one another - long-nonmotile branched microvilli3. Intercellular spaces are small
General Histology and Histotechnique (Lecture – Midterm)- Found on the surface of cells in the epididymis; Ductus deferensFunction: for absorptionc. Microvilli- Visible as striated brush borders on the epithelium of the small intestine and tubules of kidneyFunction: for absorptionLateral surface: Cell junctionsCell junctions: b. Adherens junctions (zonula adherence) - made of plaque - Form extensive bands called adhesion belts - Plaque-dense layer of proteins in the inside of plasma membrane - Composed of actin - Help epithelial surfaces to resist separation and adhesion is due to the transmembrane glycoprotein cadherina. Tight junction- It connects the cells of tissues that line the surfaces of organs and body coverings.- Specifically/specially found in intestine, urinary bladder- contain materials- Known a tights because it prevent/seal lining of organs to prevent leaking of substances towards the blood or tissues- Pose a life threatening situation c. Desmosomes (macula adherens)Location: Most apical part of epithelial - Composed of plaqueZonula – refers to the junction that forms the band. - With tonofilamentsOccludens – membrane fusions that closed of - Numerous among cells that make up the epidermisintercellular spaces. and cardiac muscle cells of the heart. - Place a role in dissipating physical forces throughout the cell thru the attachment sites. - Made of intermediate filament (keratin) - Composed of cadherin
General Histology and Histotechnique (Lecture – Midterm) Basement Membrane - Basal lamina (2 layers) + Reticular lamina Functions of Hemidesmosomes: - cell signalingd. Hemidesmosomes (hemi-half) - Proliferation- Found at the basal surface of some stratified - Apoptosis squamous epitheliaFunctions:- Connect cells to the basement membrane- Anchor one kind of tissue to another in the body.- Integrin- Presence of keratin Composition of Basal Lamina: 1. Type IV collagen - made of a 3 α chainse. Gap junction - Greatest number of protein found in our body.- The gap is bridged by transmembrane protein channels called connexons. 2. Laminin - Large glycoproteinFunctions: - Localize in lamina lucida.- Allow cell and a tissue to communicate- It enables nerve or muscle impulses to spread 3. Proteoglycans rapidly between cells. - With heparan sulfates Function: to give the basal lamina a strong anionicConnexons charge.- Made up of connexins Functions:- Individual unit of gap junctions that forms a manute - For cell attachments fluit-filled tunnels - For selective filter- Composed of connexins 4. FibronectinFunction: Form tunnels w/ different physiological - Present in small amount.properties. - Found in basal lamina - More in the lamina densa - For connecting purpose of underlying membrane.
General Histology and Histotechnique (Lecture – Midterm) 1. SimpleGeneral function of Basal Lamina - Single layer of cells Functions: Diffusion, Filtration, Absorption, secretion.1. Provide a physical support to the epithelium 2. Stratified2. Its structural support of type IV collagen gives it - 2 or more layers of cells considerable tensile strength Function: For protection for the underlying tissues3. It is flexible enough to permit stretching and recoil Ex. Skin to protect hollow organs. 3. Pseudostratified4. Provides for cell attachment by specific binding sites - False-stratified-single layer in the cell membrane - It looks like many layers. - Which may or may not possess cilia or stereocilia Reasons: - The location of nuclei is at different lavels. - Not all cells reach the apical surface Ex. Trachea - According to cell shape Classifications of Epithelia 1. Squamous – thin flat cells Functions: 2. Cuboidal – cube-shapedFunctions: Functions: Secretion & Absorption- Covering and lining 3. Columnar – Tall- cylindricalCovering - Some may have cilia- covers the body surface Function: Secretion / AbsorptionEx. EpidermisLining 4. Transitional- lines the endothelium - Cell changes in shape as the body- outer covering of body cavities (mesothelium) moves/expand/stretched.Ex. Blood vessels Ex. Urinary Bladder, UrethraGlandular Function: for Protection.- secreting portion of glandsEx. Thyroid, adrenal gland Classification according to combined cell layers and shapesTypes of epithelial tissue A. Simple Epithelium 1. Simple Squamous - Single layer of flat cells - Nucleus is located at the center - Nucleus – oval/spherical in shape Functions: - Filtration, Diffusion, Osmosis, Secretion, Absorption Location: - lining of lung alveoli, the lining of blood vessels (endothelium), Bowman’s capsule in the kidney and lining of major body cavities (mesothelium)
General Histology and Histotechnique (Lecture – Midterm) 2. Simple Cuboidal - Single layer cube-shaped cells - Nucleus – centrally located Functions: - Secretion, Absorption, covering Location: - Commonly encountered in glandular ducts, surface of ovary, kidney tubules, capsule of the lens of the eye, surface of thyroid. 3. Simple Columnar - cells appear rectangular with oval nuclei - Nuclei – found at the base or near the base. 2 forms: a. Nonciliated simple columnar - Contains microvilli and goblet cells Microvilli - absorption Goblet cells - are found in the Duodenum of small intestine to secrete mucous.
General Histology and Histotechnique (Lecture – Midterm)- Lines the GIT from the stomach to the anus, ducts of many glands and gall bladder.Functions:- Absorption, secretion, lubrication, protection. B. Stratified epithelium 1. Stratified squamous Two forms: a. Keratinized stratified squamous - keratinized Keratin – tough fibrous protein deposited in the surface of the cells. Function: Help protect the skin from heat, microorganisms, and other chemicals. - Found in the superficial layer of skin – epidermis - It is dry.b. Ciliated simple columnarGoblet cells present in the upper respiratory tract.Cilia are present for ciliary movement.Ex. Cilia in the uterine tube- Lines a few portion of upper respiratory tract, uterine tubes, uterus, some paranasal sinuses and central canal of spinal cord. b. Non-keratinized stratified squamous - It does not contain keratin - It remains moist - Lines the surface of mouth, esophagus, epiglottis, vagina, & tongue.
General Histology and Histotechnique (Lecture – Midterm) Location: - Adult sweat glands - Part of male urethra - Developing ovarian follicle 3. Stratified Columnar - Only found at the apical surface Functions: Protection and secretion - Lines part of urethra, large excretory glands, and small areas in the anal mucous membrane and part of the conjunctiva of the eye. 4. Transitional - No definite shape Apical surface - Squamous - stretched - Cuboidal columnar – relax - Lines the urinary bladder and portions of ureters and urethra. Function: To prevent distention – rupture of organs.2. Stratified Cuboidal- Rare type of epithelial tissue- Cube-shaped cells found in apical surface.Functions:- Most for protection- Limited in secretion and absorption
General Histology and Histotechnique (Lecture – Midterm) Glandular EpitheliumC. Pseudostratified Columnar Epithelium - formed by cells specialized for secretion- Nucleus is found at the base but not at the apical surface. 1. Endocrine- Lines the most upper respiratory tract, line ducts of - Ductless many glands, epididymis, and other part of male - Located in pituitary gland at the base of the brain, urethra. pineal gland in brain, thyroid and parathyroidFunctions: glands near larynx, adrenal glands superior to- For secretion kidneys, pancreas near stomach, ovaries in pelvic- Movement of mucous by ciliary action. cavity, testes in scrotum, and thymus gland in thoracic cavity. 2. Exocrine - Duct gland - Located in sweat, oil, earwax and mammary glands of the skin; digestive glands such as salivary glands which secrete into the mouth cavity; and pancreas which secretes into the small intestine – product maybe released at the skin surface or into the lumen (cavity) of the hallow organ.
General Histology and Histotechnique (Lecture – Midterm) e. Simple branched acinar - Secretory portion is branched & flask-liked Ex. Sebaceous glandClassification:a. Unicellular glands- Common example is the goblet cell- Located in the lining and glands of intestines and 2. Compound gland – branched ducts certain passages of respiratory tractFunction: To secrete mucous. a. Compound tubular - Tubular secretory portionb. Multicellular gland Ex. Bulbourethral gland, Copper’s gland- consist of more than one cellExamples: Sweat, Oil and Salivary gland b. Compound Acinar/AlveolarCategorized into two: - Flask-like secretory portion Ex. Mammary gland 1. Branched glands 2. Unbranched glands c. Compound Tubule-acinar/Tubule-alveolar - Tube-like and Flask like secretory portionMulticellular exocrine glands as to structure: Ex. Glands of pancreas1. Simple gland – single-non-branched duct.a. Simple Tubular- Secretory portion is straight and tubularEx.: Large intestine glandb. Simple Branched Tubular- Secretory portion is branched and tubular in shapeEx. Gastric gland Functional Classification of exocrine glandsc. Simple coiled Tubular *** Base on how the secretions are released:- Secretory portion is coiled and tubular.Ex. Sweat gland a. Merocrine secretion - Produce the secretory products and released it fromd. Simple Acinar/Alveolar the cells most exocrine glands.- It has a flask-like secretory portion - ExocytosisEx. Gland of phenylurethra
General Histology and Histotechnique (Lecture – Midterm)b. Apocrine secretion- Products is accumulated at the apical surface which will be pinched off then removed apex to released secretionsc. Holocrine- Secretory products accumulate at the apical surface which will pinched off.Adenocarcinoma – developed from glandularepithelium.