Question

Differences and similarities of the developmental stages: blastulation, gastrulation and neurulation of the human, chicken and frog

Answer 1

	Human	Chicken	Frog
1.Blastulation 2.Gastrulation	In blastulation blastula forms from morula.Morula is filled with evenly spread cells known as blastomeres but in blastula there is fluid filled cavity known as blastocoel.In human blastula is called as Blastocyst which consist of inner cell layer, trophoblast and a blastocoel. Blastocoel is filled with the watery fluid which is secreted by trophoblast cells. In human blastocyst is formed in 5 to 6 days after fertilization. During the third week of human development gastrulation occurs.A multicellular structure forms from a single layerd blastula known as gastrula.Gastrula is three layerd structure. Three germ layers are known as Ectoderm, Mesoderm and Endoderm. Gastrulation is followed by Organogenesis.	In chicken after cleavage , blastulation occurs and in blastulation following structures are formed- Sub germinal cavity- It is similar to blastocoel. Area pellucida- It is the traslucent center area of blastoderm. It forms the proper body. Area opaca- It is the opaque area of blastoderm.It is present arround the area pellucida. It helps in the formation of extra embryonic membrane known as Yolk Sac. gastrulation process is similar to humans.	Blastula consists of solid ball of cells known as blastomeres. The blastula of frog is known as amamphiblastian.The blastula of frog is hollow and it has a very well developed blastocoel. So it is known as Coeloblastula. There are two differences between human and frog. In frog the blastula is not hollow but filled with yolk sac the other difference is that the cells in the blastula of frog forms ectoderm or endoderm. While the mesoderm is formed from yolk cells.
neurulation	neurulation involves formation of neural tube from folding of nural pervous system.late .then finally central n	similar to humans	similar to humans

SIMILARITIES-Basically all have similar features but due to special organ development they have differences.Some have lungs other have gills.so they are all different.