Chapter 43, Problem 2AC

Summary Introduction

To explain:

The reason for the difference in shape of animal eggs which have little egg yolk and spherical blastula stage as compared to the mammalian eggs which have flat embryonic discs and virtually no egg yolk.

Introduction:

Animal eggs contain large amounts of yolk with formation of animal pole and vegetal pole. There is a blastocoel cavity with formation of deep cells and superficial cells formed during the process of cell division. There is a formation of dorsal blastopore lip during which forms archenteron, mesoderm and endoderm. Mammalian eggs have less amount of yolk which is a source of the supply of lipids and nutrients in the blood.