1. Embryonic Development of Chickens
By: Ms. Ryan

2. Fertilized Unincubated Egg
Infertile Egg

3. Before Egg Laying Fertilization Division and growth of living cells
Segregation of cells into groups of special function (tissues)

4. Between Laying and Incubation
No growth
Stage of inactive embryonic life

5. During Incubation: Day 1
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

6. Day 1

7. During Incubation: Day 2
25 hours – beginning of heart
35 hours – beginning of ear
42 hours – heart beats

8. Day 2

9. During Incubation: Day 3
60 hours – beginning of nose
62 hours – beginning of legs
64 hours – beginning of wings

10. Day 3

11. Incubation: Day 4 Beginning of tongue
Entire body turns 90 degrees and lies down with its left side on the yolk
Head and tail come close together to make a “C” shape
Heart continues to enlarge
Other internal organs continue to develop
Should have all organs by the end of this day

12. Day 4

13. Incubation: Day 5
Formation of reproductive organs and differentiation of sex
Male or female

14. Day 5

15. Incubation: Day 6
Beginning of beak

16. Day 6

17. Incubation: Day 7 Digits appear on wings and feet
Heart is completely enclosed in the thoracic cavity
Embryo looks more like a bird

18. Day 7

19. Incubation: Day 8
Beginning of feathers

20. Day 8

21. Day 9

22. Incubation: Day 10 Beginning of hardening of beak
Feathers and feather tracts are visible

23. Day 10

24. Day 11

25. Day 12

26. Incubation: Day 13
Appearance of scales and claws

27. Day 13

28. Incubation: Day 14
Embryo gets into position suitable for breaking shell
Claws are forming

29. Day 14

30. Day 15

31. Incubation: Day 16
2nd per. 2/10
Scales, claws, and beak becoming firm and further developing

32. Day 16

33. Incubation: Day 17
Beak turns toward the air cell

34. Day 17

35. Day 18

36. Incubation: Day 19 Yolk sac begins to enter body cavity
Acts as nutrition for the chick when it hatches
This is why it is okay to leave chicks that have hatched in the incubator for up to 2 days

37. Day 19

38. Incubation: Day 20 Yolk sac completely drawn into body cavity
Embryo occupies practically all the space within the egg except the air cell
Chick is in hatching position
Beak has pierced the air cell
Pulmonary respiration has begun

39. Incubation: Day 21 Hatching of the chick!
Chick begins pushing its beak through the air cell
Allantois (served as the lungs) beings to dry up and chick uses its own lungs
Egg tooth and muscle on the back of the neck help cut the shell
Kicks free from bottom portion of shell
At this point its exhausted!
Rests until down dries and it has strength to stand

40. Day 21