INTRODUCTION -

• Fertilization is a complex process which involves fusion of male & female gametes.
• The male gamete in animals is called as sperm & the female gamete as ovum.
• Albert Tiler - Fertilization is a sequence of various events initiate through sperm.
• Austin - The fusion of male & female gametes to form zygote is called as fertilization.
• O. Hertwig - Fusion of male & female pronuclei is called as fertilization.
• Syngamy - Fusion of gametes in the fertilization is called as syngamy.
• Plasmagamy - Fusion of the cytoplasm of gametes.
• Karyogamy - Fusion of nucleoplasm.
• On the basis of shape & size gametes are two types -

                    1. Isogamy - In this male & female gametes are similar.

                    2. Anisogamy - The male & female gametes are different.

• Genetically contribution of male & female gametes is equal.
• According James Grey fertilization essential for -

1. Activation -

In this process cortex of egg activated & formed the fertilizine membrane over P.M.

Cytoplasm of ova initiate different metabolic activities, this activities essential for initiate cleavage.

2. Amphimixis -

In this process male & female pronuclei are fused and formed the diploid structure, i.e. zygote.

Genetic variation stimulate in the species.