Sunday 21 February 2016

STRATIFIED EPITHELIUM (COMPOUND EPITHELIUM)

*cellls arranged in more than one layer.
*basal layer of the tissue are either cuboidal or columnar , never squamous, so it is further classified into three types on the basis of cells present on its upper surface-

  1. Compound squamous epithelium/ pavement
  2. Compound columnar epithelium
  3. Compound squamous epithelium
1. Compound squamous epithelium-this type of epithelium contains, squamous cells on free surface, it is further classified into two group on the basis if Keratin protein.

#Compound keratinised squamous epithelium-it contains keratin protein, hence it is hard and dead. e.g.-epidermis of skin.

#Compound non-keratinised squamous epithelium-it does not contain keratin protein, so it is relatively soft. it is present at all opening of the body which communicate with environment like mouth, anus ,nasal opening,ear opening, urinogenital opening.


2. Compound cuboidal epithelium-this type of epithelium contains cuboidal cells on free surface.
e.g.-testis, ovary

3.Compound columnar epithelium-this type of epithelium contains columnar cells on its free surface.
e.g.- epiglottis, gullet, larynx,pharynx,oesophagus(all parts are of food track).


SPECIAL TYPE OF EPITHELIAL TISSUE

A. Pseudo-stratified epithelium- cells arranged in single layer, but it apopears like arranged in more than one layer. e.g.-it is found near pharynx.

B. Transitional epithelium-these epithelium do not contain basement membrane. in this type of epithelium cells are arranged in 4-5 layers, and cells of each layer have different function. e.g.- urethra, urinary bladder.