Question

Does the gastrula stage look the same between an amphibian and a bird? How about the beginning of nervous system development? Are the embryos the same size at the same point in development? Does one type of embryo develop more quickly than the other?

Answer 1

There is no much difference in gastrula as both are triploblastic animals but the gastrulation is different from amphibian to the bird, in amphibians after the formation of the blastula, the gastrulation begins with the movement of the surface cell into the interior as rolling as a sheet called involution, while it is by internalization or separation of cells from epithelium called ingression. Amphibians gastrula is a hollow ball of cells while in birds it flat shaped.

The beginning nervous system development is same in both birds and amphibians, after neural plate formation, its edges thicken to move upward to form the neural folds.

The amphibian embryo develops faster than birds as Amphibian embryo takes 12hrs from Zygote to neurulation. while in birds the total embryonic development takes place from 21 to 32 days.