Egg Incubation Physiology - Anatomy & Physiology

Changes in Composition of the Egg during Incubation

As the embryo grows within the egg, the composition of the egg changes.
Both yolk and albumin diminish.
- Yolk providing energy for growth and maintenance of the embryo.
- Albumin providing protein for the embryo and giving up water, which is lost through pores in the shell.
Water is produced when yolk fat is oxidised.
Water lost from the egg is replaced by air, creating the 'air cell' at the blunt end of the egg.
Embryo punctures the chrioallantoic and internal shell membrane.
- Able to begin pulmonary ventilation, rebreathing the 'air cell' gas.
- Transition from diffusive respiration through the chorioallantois to breathing through the lungs.