Скачать или смотреть Sexual Reproduction in Animals|Spermatogenesis & Oogenesis | Chap # 14| Biology Class 10| Lec # 10

Gametogenesis is the process by which specialized reproductive cells called gametes are produced in animals. Gametes are essential for sexual reproduction as they combine during fertilization to form a new individual with a unique combination of genetic material. Gametes are haploid cells, meaning they contain half the number of chromosomes as the parent cell.

In animals, gametogenesis occurs in specialized organs or structures called gonads. In males, the gonads are the testes, and in females, they are the ovaries.

Here's an overview of gametogenesis in both males and females:

Spermatogenesis (Males):
Spermatogenesis is the process of gamete formation in males. It occurs within the seminiferous tubules of the testes and involves several stages:

a. Spermatogonia: These are the diploid precursor cells present in the testes. They undergo mitotic divisions to form primary spermatocytes.

b. Primary Spermatocytes: These diploid cells undergo meiosis I to form two secondary spermatocytes.

c. Secondary Spermatocytes: These haploid cells undergo meiosis II to produce four haploid spermatids.

d. Spermatids: These are immature gametes that undergo further changes, including development of a tail (flagellum) and reduction of cytoplasm, to become mature, motile sperm cells.

Oogenesis (Females):
Oogenesis is the process of gamete formation in females. It occurs within the ovaries and involves a series of developmental stages:

a. Oogonia: These are the diploid precursor cells present in the ovaries. They undergo mitotic divisions to form primary oocytes.

b. Primary Oocytes: These diploid cells are arrested in prophase I of meiosis until puberty. Each month, one primary oocyte is activated and completes meiosis I, resulting in one large secondary oocyte and a smaller polar body.

c. Secondary Oocyte: The secondary oocyte is released from the ovary during ovulation. If fertilization occurs, meiosis II is completed, resulting in a mature ovum (egg cell) and another polar body. The mature egg is now ready for fertilization.

It's important to note that while males continuously produce sperm throughout their reproductive lives, females are born with a finite number of primary oocytes, which are gradually depleted over time. This is why the potential for egg production decreases with age.



#biologyclass10th
#biologyworld
#biologylecture
#biologyeducation