Embryonic Development of Chickens By: Ms. Ryan
Fertilized Unincubated Egg Infertile Egg
Before Egg Laying Fertilization Division and growth of living cells Segregation of cells into groups of special function (tissues)
Between Laying and Incubation No growth Stage of inactive embryonic life
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
Day 1
During Incubation: Day 2 25 hours – beginning of heart 35 hours – beginning of ear 42 hours – heart beats
Day 2
During Incubation: Day 3 60 hours – beginning of nose 62 hours – beginning of legs 64 hours – beginning of wings
Day 3
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
Day 4
Incubation: Day 5 Formation of reproductive organs and differentiation of sex Male or female
Day 5
Incubation: Day 6 Beginning of beak
Day 6
Incubation: Day 7 Digits appear on wings and feet Heart is completely enclosed in the thoracic cavity Embryo looks more like a bird
Day 7
Incubation: Day 8 Beginning of feathers
Day 8
Day 9
Incubation: Day 10 Beginning of hardening of beak Feathers and feather tracts are visible
Day 10
Day 11
Day 12
Incubation: Day 13 Appearance of scales and claws
Day 13
Incubation: Day 14 Embryo gets into position suitable for breaking shell Claws are forming
Day 14
Day 15
Incubation: Day 16 2nd per. 2/10 Scales, claws, and beak becoming firm and further developing
Day 16
Incubation: Day 17 Beak turns toward the air cell
Day 17
Day 18
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
Day 19
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
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
Day 21