What’s happening to the chick on Day 8?

The third eyelid, a transparent membrane which keeps the eye moist and free from grit is developing today. It’s clear so that the chicken can keep an eye open – literally – for predators even as it blinks.

The pterylae or feather tracts – the part of the chicken’s body from which the feathers sprout – are developing today and the down the chick will be born with, known as natal down, is growing.

Day 8

What’s happening to the chick on Day 4?

On the fourth day the chick’s entire body turns and lies down with its left side on the yolk. The head and tail come close together so the embryo forms a “C” shape. The mouth, tongue, and nasal pits develop as parts of the digestive and respiratory systems. The heart continues to enlarge even though it has not been enclosed within the body.  By the end of the fourth day of incubation, the embryo has all organs needed to sustain life after hatching, and most of the embryo’s parts can be identified.

Day 4