EALS 2nd QTR (Sexual Reproduction in Animals)

Sexual Reproduction

It involves male and female parents to produce offspring through the fusion of gametes (sperm and egg cells) generated by meiosis.

Gametogenesis

Two Stages of Sexual Reproduction

•It is the formation of male and female gametes.

•Types: spermatogenesis and oogenesis

Spermatogenesis

Two Stages of Sexual Reproduction

•It is the formation of sperm cells in males.

•It takes place in the testes.

Oogenesis

•It is the formation of egg cells in females.

•It takes place in the ovaries.

Fertilization

•It is the union of male and female sex cells.

•Types: external and internal

External Fertilization

It is the union of egg and sperm occurs outside the female reproductive tract.

Internal Fertilization

•It is the union of egg and sperm occurs within the female reproductive tract.

•This type is common in most sharks, birds, aquatic reptiles, and mammals.

Types: oviparity, ovoviviparity, and viviparity

Oviparity

The eggs are fertilized internally and receive nourishment through their yolk.

Ovoviviparity

The eggs are fertilized internally, and they complete their development within the mother. The zygotes grow into embryos, which receive their nourishment through the yolk.

Viviparity

The eggs are fertilized internally. The embryos receive nourishment directly from the mother’s blood through the placenta rather than from the yolk.

Post-fertilization

The fertilized egg undergoes a series of cell divisions termed as cleavage.

Cleavage

is a series of extremely rapid mitotic divisions wherein large volume of cellular materials are divided into multiple smaller cells.