THE EPITHELIAL TISSUE Prepared by : Reem Aldossari Lab 2 ZOO 103

Structure closely packed cells Specialized to cover external surfaces or line internal cavities. Epithelial cells are packed tightly together, with almost no intercellular spaces and only a small amount of intercellular substance. Rest on Basement Membrane o thin sheet of connective tissue o provides structural support for the epithelium o binds it to neighboring structures Functions : Protection Permeability Sensations Secretions

Types of Epithelial Tissue Epithelial tissue can be divided into two groups depending on the number of layers of which it is composes. simple epithelium: which consist of only one layer squamous epithelium cuboidal epithelium columnar epithelium StomachIntestine Collecti ng tubule Thyroid gland Lining of Mouth Top view Bowman’s capsule Side view stratified epithelium: which consist of more than one layer ( Squamous,cuboidal,columna r) Skin of Toad ( Frog )

Covering “surface” epithelium. Glandular epithelium Neuro_epithium Types of Epithelial Tissue The Simple. Stratified. epithelium of cells specialized to produce secretion. (Goblet cell) Epithelial tissue can be divided into two groups depending on their function of which it is composes.

Simple epithelium Simple epithelium can be subdivided according to the shape and function of its cells. Squamous epithelium Squamous cells have the appearance of thin, flat plates. Squamous cells tend to have horizontal flattenednuclei because of the thin flattened form of the cell. They form the lining of cavities such as the mouth, blood vessels, heart and lungs and

Squamous epithelium

cuboidal cells are roughly square or cuboidal in shape. Each cell has a spherical central nucleus. Cuboidal epithelium is found in glands lining of the kidney tubules ducts of the glands Simple Cuboidal Epithelium

The cells are elongated and column-shaped. The nuclei are elongated and are usually oval and basal. Columnar epithelium forms the lining of the stomach and intestines. Simple Columnar Epithelium

Glandular Epithelium: epithelium of cells specialized to produce secretion. All glands are of composed of epithelium. columnar and cuboidal epithelial cells. Glandular Epithelium 1 2

Under The Microscope

Simple Squamous Epithelium ( Lining of mouth ) 1- Cell membrane 2- Cytoplasm 3- Nucleus 1 2 3

Simple Cuboidal Epithelium 1-Nucleus 2-Basement membrane 3-Cuboidal cell 4-Collecting Tubules T.S of (collecting tubule (in the kidney T.S of Thyroid gland

Simple Columnar Epithelium 1-Nucleus 2-Plasma membrane 3-Basement membrane T.S of intestine

Epithelium tissues (Goblet cells ) 1-Goblet cells 2-Villi 1 2