The egg is formed inside the ovary of the hen. It moves to the infundibulum, where a large number of sperm awaits it; only one of them can fertilize the egg to form a fertilized egg. While it is inside the warm body of the chicken, the fertilized egg begins to divide to form two cells to produce four partitions, then, then eight. Sixteen cells, and so on until a group of cells is formed that gather in a small white spot on the upper surface of the yolk to create the germ disk, and within 24 hours of fertilization, the hen lays the egg.
Stages of development of a chicken egg embryo
The following are the most critical developments that occur to the fetus during the incubation of the hens for eggs:
The first day: A group of cells at the caudal end of the fetus transform into a primitive chain that extends along the longitudinal axis of the fetus, from which the head and spine of the fetus are formed, the digestive canal begins to form, the islets of blood appear that will later create the blood vessels, and the eyes start to form.
On the second day: the blood vessels and the heart are formed, and after 44 hours of laying the egg, the heart begins to beat, and two circulatory systems are formed: the first is embryonic, and the second is viviparous.
On the third day: the beak appears, and the wings and legs begin to occur by the end of the third day.
Fourth day: The head and tail are close to each other, so that the fetus becomes in the shape of a letter (C), the mouth, tongue, and nasal holes develop, and the size of the heart increases, but it remains at this stage outside the body, and by the end of the fourth day, the fetus possesses all the organs necessary to maintain life after hatching.
The seventh day:
The fingers appear on the legs.
The wings begin to differentiate.
The heart becomes inside the thoracic cavity.
The fetus acquires the shape of a bird.
The tenth day – the twentieth day: Feathers appear on the wings after the tenth day, and the beak becomes solid, and on the fourteenth day, the claws are formed, and the fetus begins to move until it reaches the hatching position, and on the twentieth day, the beak pierces the air chamber in the egg and begins pulmonary respiration.
Chicken eggs hatching
A chicken chick uses the egg tooth to break the eggshell and find a way out. It may take the chick between 4-12 hours to get rid of the body, and when it comes out, it is wet and tired, and it remains silent for a period of up to several hours until it dries. It relaxes, then begins to move and vigorously while the egg dries up and falls.
Three membranes are formed inside a chicken egg; Which:
Yolk sac: provides the fetus with food inside the egg.
The amniotic membrane: surrounds and protects the fetus.
Lakkanqi or Manbar: works like a respiratory system and removes the egg from waste and minerals through the shell.