Avian Embryology

2. Embryology:-
 Embryology is study of development of an organism
from time and egg is fertilized until the time when all
major organ, systems are formed.
 Embryological processes:-
 Embryological processes involved
1-Fertilization.
2-Cleavage
3-Blastulaion
4-Gasturalation

3. Different events occur in embryonic
development: Before Laying of Egg
 Fertilization occur
 living cells Division and growth
 Cells Segregation into groups (tissues)
In Between Lying and Incubation:-
 No growth occur; inactive embryonic life stage

4. Contii…
Day One
 At 25 hours - initiation of ear
Day Three
 At 60 hours - initiation of nose
 At 62 hours - initiation of legs
 64 hours - initiation of wings
Day Four
 Initiation of tongue
 All body organs are present
 The vascular system is clearly evident to naked eyes

5. Contii…
Day Five
 Formation of reproductive organs takes place and
differentiation of sex
 Heart begin to take a definite shape & vascular area of
yolk sac covers 2/3 of yolk
Day Six
 Beginning of beak and egg tooth
Day Seven
 Rapid development of embryo
 Body organs ar clearly visible

6. Contii…
Day Eighth
 Initiation of feather
Day Ten
 Hardening of beak
 Toes & scales appears on legs
Day Eleven
 The walls of abdomen appear and intestine may be
seen in yolk

7. Contii…
Day Thirteen
 The skeleton is beginning to calcify
 Most organs are differentiated clearly
Day Fourteen
 The embryo rotate to take the normal position (Head
toward broader end)
Day Seventeen
 Embryo rotate to take the right position (Beak is under
right wing)

8. Contii…
Day Nineteen
 The yolk sac begin to enter the body cavity
 The chick rotate to find a position necessary for Pipping
the shell
Day Twenty
 Yolk sac completely drawn into the body cavity
 Embryo occupy all the space within the egg except the air
cell
 The beak of chick penetrates the inner membranes and
enter the air cell
 Chick inhales some air and pulmonary respiration begins
 Chick pips to shell to gain entrance to outside air
 At this time the lungs become fully functional

10. Contii…
Day twenty one
 Pipping and Muscular movement of embryo create a
circle cut around the whole shell
 Hatching of chicks

11. e