Question

list the vaious steps that lead to the form ation of eggof a hen

Answer 1

zygote
morula-embryo
blastula-embryo
gastrula-embryo
First day:
16 hours - first sign of resemblance to a chick embryo
18 hours - appearance of alimentary tract
20 hours - appearance of vertebral column
21 hours - beginning of nervous system
22 hours - beginning of head
24 hours - beginning of eye

Second day:
25 hours - beginning of heart
35 hours - beginning of ear
42 hours - heart beats

Third day:
60 hours - beginning of nose
62 hours - beginning of legs
64 hours - beginning of wings

Fourth day - beginning of tongue

Fifth day - formation of reproductive organs and differentiation of sex

Sixth day - beginning of beak

Eighth day - beginning of feathers

Tenth day - beginning of hardening of beak

Thirteenth day - appearance of scales and claws

Fourteenth day - embryo gets into position suitable for breaking shell

Sixteenth day - scales, claws and beak becoming firm and horny

Seventeenth day - beak turns toward air cell

Nineteenth day - yolk sac begins to enter body cavity

Twentieth day - yolk sac completely drawn into body cavity; embryo occupies practically all the space within the egg except the air cell

Twenty-first day - hatching of chick