What is the Fate of excretory material inside eggs hens?

Inside eggs, hens, or any other avian species, the fate of excretory materials is tightly controlled and differs from the excretory processes in mammals.

1. Nitrogenous Wastes:

- Initial Accumulation: During embryonic development, nitrogenous wastes, primarily in the form of ammonia, are initially stored within the embryo itself.

- Uric Acid Synthesis: As the embryo develops, its liver begins to synthesize uric acid from the breakdown of proteins and amino acids. Uric acid is less toxic than ammonia and aids in water conservation.

- Allantoic Sac: The allantoic sac, an extraembryonic membrane, accumulates the uric acid and other nitrogenous waste products. The allantoic sac also assists in gas exchange, aiding in the transfer of oxygen from the hen to the embryo.

2. Formation of Feces:

- Waste Accumulation: As the hen's digestive system develops within the egg, waste materials, such as undigested yolk, and other solid metabolic waste products, accumulate in the large intestine.

- Water Absorption: The cecal pouches in the large intestine help in the absorption of water from the waste, making the feces semi-solid.

3. Storage and Hatching:

- Cloaca: The cloaca, a common opening for the digestive, reproductive, and excretory systems, is the site where the semi-solid feces, along with the allantoic sac containing uric acid, are stored until hatching.

- During Hatching: At hatching, the chick releases both feces and uric acid from the cloaca. This waste material is expelled as the chick takes its first breaths of oxygen.

It is essential to note that the eggshell acts as a protective barrier, preventing any significant exchange of waste products between the embryo and the external environment. The efficient storage and elimination of excretory materials within the egg shell are critical for the survival of the developing embryo and successful hatching.