Course Content
Human Population and Health Disorder
0/2
Invitro Fertilization and Amniocentesis
0/2
Vaccine
0/1
Antibiotics
0/1
Transgenic animals
0/1
Animal Husbandry
Class 12
About Lesson

Gametogenesis:

The process of formation of gametes in the gonad is called gametogenesis (sperm in testis & ova in ovary).

Spermatogenesis:

The process of formation of sperms is known as spermatogenesis. This process is distinguished into three phases.

  1. Multiplication phase
  2. Growth phase
  3. Maturation phase.

 

  1. Multiplication phase:

Each seminiferous tubules of testis is lined with germinal cells. The germ cells multiply repeatedly to form spermatogonia containing diploid number of chromosomes (2n)

2. Growth phase:

The spermatogonia increase in size by the accumulation of nourishing material & attain maturity and mature spermatogonia are termed as

primary spermatocytes.

3. Maturation phase:

Each primary spermatocyte under goes reduction division (meiotic-I) to form secondary spermatocytes and secondary Spermatocytes again undergo mitosis division to form spermatids. Each spermatid later on metamorphoses into a sperm which has a small head with a nucleus & a long tail.

Oogenesis:

The process of formation of ova from the germ cells of the germinal epithelium of ovary is called oogenesis. It is completed in three phases.

  1. Multiplication phase
  2. Growth phase
  3. Maturation phase

 

  1. Multiplication phase: The primary germ cells of the germinal epithelium undergo repeated divisions & ultimately form the oogonia.
  2. Growth phase: In this phase oogonia increases in size by the accumulation of yolk to form primary oocytes.

  3. Maturation phase: The primary Oocytes undergo two successive divisions. The first maturation division by meiotic to form a secondary oocyte. The second maturation division takes place with an unequal division of the cytoplasm, resulting in the formation of a large ovum & small second polar body.
Join the conversation