Torsion: The 24 hours chick embryo is flat. Its ventral surface is in contact with yolk. As the development proceeds the anterior end of embryo is turns towards right and hence the anterior part of embryo comes to lie on the left side of yolk. This twisting is called torsion. At the end of 48 hours chick twisting will reach the cervical flexure. It is nearly at 13th somite.
Ear: The invagination of optic vesicle is completed. It is connected to ectoderm by endolymphatic duct.
Blood vessels: From the anterior end of heart two ventral aortae will arise. They run backwards and travel as dorsal aortae.
Kidney: Pronephrous is completely developed. Mesonephric tubules started development.
Somites: At 48 hours of incubations 25 pairs are seen. Mesonephric tubules will develop from intermediate mesoderm.
BLOOD ISLANDS: Around the area pellucida, area opaca is present. In this opaca region groups of mesenchyme cells will present. They are called blood islands. They produce embryonic blood vessels.
- FRESHLY LAID HEN'S EGG
- CHICK EMBRYO AT 24 HOURS
- CHICK EMBRYO AT 48 HOURS
- GASTRULATION IN CHICK-I
- GASTRULATION IN CHICK-II - FORMATION OF ENDODERM
- GASTRULATION IN CHICK-III - FORMATION OF PRIMITIVE STREAK & MESODERM
- GASTRULATION IN CHICK-IV - DEVELOPMENT OF MESODERM AND COELOME
- CHICK: EXTRA EMBRYONIC MEMBRANES