In this article we will discuss about the analysis of nature and action of organizer in amphibian eggs. Grey crescent—its Role in Development: Wilhelm Roux (1888) first described the grey crescent in amphibian egg. The experiments of Rund and Spemann have emphasised the vital role of grey crescent in amphibian development (see Fig. 5.14). If the egg is surgically divided [...]
In this article we will discuss about:- 1. Meaning of Cleavage 2. Planes of Cleavage 3. Types 4. Effects of Yolk 5. Mechanism 6. Chemical Changes 7. Different Chordates 8. Importance in Embryonic Pattern. Contents: Meaning of Cleavage Planes of Cleavage Types of Cleavage Effects of Yolk in Cleavage Mechanism of Cleavage Chemical Changes during Cleavage Cleavage in Different Chordates [...]
In this article we will discuss about:- 1. Meaning of Extraembryonic Structures in Chick Embryo 2. Formation of Yolk Sac and its Fate 3. Formation of Amnion and Serosa 4. Formation of Allantois. Meaning of Extraembryonic Structures in Chick Embryo: The embryo of chick possesses four extraembryonic or foetal membranes: namely, the yolk sac, the allantois, the amnion and the [...]