Histology
Histology
IntroductionDefinition of Histology :to study the fine structureassociated with its function in the human body.Contents:cells (basic units of structure)and intercellularsubstanceTissues(epithelial,connective,muscleand nervous)Imorethan2kindsoftissuesXOrgansX organs with related functionsXSystemsX
Introduction ❖ Definition of Histology : to study the fine structure associated with its function in the human body. Contents: cells (basic units of structure) and intercellular substance ❖ Tissues (epithelial, connective, muscle and nervous) ❖ more than 2 kinds of tissues ❖ Organs ❖ organs with related functions ❖ Systems
Epithelial Tissue (ET)Characteristics:1.Membrane-like structure: crowded cells with very scantyintercellular substance.2. Polarity: basal end rests on the basement membrane (BM)the distal end associates with functions, e.g. absorption(microvillibyEM,striatedboarderbyLM),secretion(glandgoblet cell, acinus) and etc3.Avascular: in general ET has no blood vessels, may be richin nerve endings
Epithelial Tissue (ET) ❖ Characteristics: 1. Membrane-like structure: crowded cells with very scanty intercellular substance. 2. Polarity : basal end rests on the basement membrane (BM), ❖ the distal end associates with functions, e.g. absorption (microvilli by EM, striated boarder by LM), secretion (gland: goblet cell, acinus) and etc. 3. Avascular: in general ET has no blood vessels, may be rich in nerve endings
ClassificationofEpithelia 1. The simple epithelium (each cell rests on BM) mainlyassociated with lubrication,transport,absorption orsecretion function.It canbe divided into:(1). Simple squamous epithelium (e.g.endothelium)(2). Simple cuboidal epithelium (renal tubules)(3).Simple columnar epithelium (intestinal inner-surface)(4).Pseudostratifird (cilliated) columnar epithelium(trachea inner-surface)
Classification of Epithelia ❖ 1. The simple epithelium (each cell rests on BM) mainly associated with lubrication, transport, absorption or secretion function. It can be divided into: ❖ (1). Simple squamous epithelium (e.g.endothelium) ❖ (2). Simple cuboidal epithelium ( renal tubules) ❖ (3). Simple columnar epithelium (intestinal inner-surface) ❖ (4). Pseudostratifird (cilliated) columnar epithelium ❖ ( trachea inner-surface)
： 2.The stratified epithelium (multi-layers contain deepmiddle and superficial layers, onlythebasal cells rest onBM),mainly associated withprotection function.Based ontheshapeof thesufacecells,itcanbedividedinto(1)Stratifiedsquamousepithelium:non-keratinized(esophageal inner-surface),keratinized(skinepidermis)(2)Stratified cuboidepithelium(3)Stratified columnarepithelium(4)transitional epithelium (urothelium):relaxed)stretched,maybepseudostratified
❖ 2. The stratified epithelium ( multi-layers contain deep, middle and superficial layers, only the basal cells rest on BM), mainly associated with protection function. Based on the shape of the suface cells, it can be divided into: ❖ (1)Stratified squamous epithelium : non-keratinized (esophageal inner-surface), keratinized (skin epidermis) ❖ (2) Stratified cuboid epithelium ❖ (3) Stratified columnar epithelium ❖ (4) transitional epithelium (urothelium): relaxed stretched, may be pseudostratified