Hens lay no more than one egg per day as the process of laying an egg is governed by the presence of sunlight. The lack of natural light during the winter months means that even fewer eggs are laid during this time of the year. Humans can, however, ‘trick’ chickens into laying despite the limited sunlight by adding artificial light (such as a light bulb) to the coop. The laying process starts when light entering the hen’s eye activates a photosensitive gland (the pineal gland) positioned nearby. Once stimulated, this gland triggers a process that leads to the release of an egg, or oocyte, from the hen’s ovary. An egg can still be laid whether or not it has been fertilised by a male, but only fertilised eggs can develop into chicks. The orifice through which the egg leaves the hen is called the vent. Though this hole also forms the outlet for waste by-products (ie urine and faeces), there is a valve called the cloaca which separates the oviduct from the intestine.
The chick starts out as a single cell that divides and forms a hollow disc on the surface of the yolk. This yolk is then released into a spiralling oviduct tube. As it travels down the oviduct it builds up a number of layers, including a vitelline membrane directly surrounding the yolk, and two layers of viscous white albumen divided by a structural fibrous layer. Lower in the oviduct tube the eggshell layer develops around the yolk, protecting it and giving it form. When the egg is expelled from the body so begins the following 21-day period of embryonic development…
Govind. K
Kalagramam General Conveener
Mind Garden 