Chick Development

The development of the chick typically occurs over 21 days. The ovum is internally fertilized in the oviduct and, as it travels down, develops the albumen and membranes that become the hard exterior shell. 24 hours post-fertilization, the egg is laid by the mother. A chicken can lay one egg a day, depending on the amount of sunlight. She sits on the egg to incubate it over the next three weeks to maintain a temperature of 99 degrees Fahrenheit

Chick Development Ex Ovo

(CD Stern, 2005)

Stages of development in the chick have been best described by Viktor Hamilton and Howard L Hamilton. They have classified specific changes and migrations in development over hours of chick development. The staging has become the standard for post-fertilization milestones. Below is the table that illustrates the stages and a reference photo for each stage. Hamilton and Hamburger.

Based on this information, it’s hard to see any potential advantages to relate to human disease, so we ask,

why are chicks used as a model organism for humans?

Advantages of the chick model are that they are relatively inexpensive to produce. Due to facility restraints of raising chickens in designated coops, fertilized eggs are typically ordered through a company. Maintaining the eggs is easy where a designated facility (such as a fishery or mouse cages) are not needed. The eggs should just be kept at an appropriate temperature.

Observation of the embryo is possible while still maintaining its environment in the egg, it’s even possible to maintain development ex o o. This allows for continuous monitoring of the same organism throughout its development. As opposed to other organisms, such as mice, where a different litter would need to be used for each stage. This keeps samples and data consistent with less variation.

Other techniques used in chicks are electroporation, which uses electricity to integrate DNA into the organism. This is easily done in ovum of the chick. Another technique is transplantation of quail tissue to create a chick/quail chimera. Because of the differences in chromatin distribution in the cell, the quail cells can be used as markers in development.