1. Types of eggs Eggs classified according to the amount or distribution of yolk. According to the amount of yolk, the egg arranged into the following: 1.Alecithal : Without yolk. eg. mammal 2.Oligolecithal : Small amount. eg. amphioxus 3.Mesolecithal: Moderate amount. eg. toad 4.Polylecithal : Large amount. eg. Bird According to distribution of yolk : 1.Homolecithal: The yolk equally distributed throughout the cytoplasm. Eg. Amphioxus. 2.Centrolecithal: The yolk concentrated in a net like structure arround the nucleus. Eg. Insects. 3.Telolecithal: The yolk deposited in vegetal pole. Light telolecithal type with moderate amount of yolk (eg. Toad). Heavy lellecithal type with large amount of yolk (eg. Bird).

2. 1.Holoblastic cleavage: a. Equal holoblastic: The zygote gives two equal blastomeres. Eg. Amphioxus. b. Unequal holoblastic: The zygote give two unequal blastomeres. Eg. Toad. 2.Superficial cleavage: The nucleus divides into several ones which migrate toward the surface which surround by cytoplam.eg. Insects. 3.Discoidal cleavage : Localized in germinal disc. Eg. Birds. Pattern of cleavage

8. Superficial Cleavage Birds