Notes of class 7

Animal tissue :- There are four major types of animal tissue :-

(i) Epithelial tissue :- [ Epi = Upper ; Thelium = Layer ]

Epithelium is covering on internal tissue. It is protective in function. All types of epithelial tissue are situated on the basement membrane. On the basis of its structure and location there are three types of epithelial tissue.

(A) Squamous epithelium :- 

• Squamous epithelial cells are flat, irregular.
• It is also called pavement epithelium.
• This tissue is present on outer layer of skin, lining of alveoli, blood vessels, body cavity.
• Squamous epithelium is involve in protection of underlying tissue.

(B) Cuboidal epithelium :- 

• Cells of this tissue is cube like.
• It is found as single layer.
• Each cell of cuboidal epithelium has single nucleus in it.
• Cuboidal epithelium is found on the lining of kidney tubule, thyroid gland, germinal epithelium in testes and ovaries.
• Main function of cuboidal epithelium is secretion and absorption.
• In testes ( found in male ) and ovaries ( found in female ), cuboidal epithelium is involve in production of male gamete ( sperm ) and female gamete ( ovum ).