Gallus gallus domesticus (Chick)
The Chick is a widely used model organism, it has been applied in various areas of science but its main roles have been in research into embryological 
development and genetic disease. The Chicks genome was the first avian genome to be mapped due to its importance in medical research and as a commercial product, its genome is highly conserved with ours, making it an ideal model organism.
Development of the Chick after fertilisation occurs in an egg outside of the maternal organism making it easy to study and requiring very little care. The embryo develops for 21 days inside the egg after fertilisation before it hatches.
Advantages of the Chick as a model organism:
- Cheap to keep in the laboratory.
- It is a healthy species and so can survive in a reasonable range of conditions.
- It is unlikely to be susceptible to disease whilst under experimental conditions.
- The embryo develops outside of the organism, once hatched.
- The Chick has a mapped genome, which is highly conserved with our own.
- Large structures in the embryo, making changes easy to view.
Disadvantages of the Chick as a model organism:
- Small batch sizes.
- The early embryo develops inside of the organism before the egg is hatched at ~20 hours post fertilisation.
The Chick in medical research:
The Chick can be found in labs worldwide and is a heavily used model organism, the focus of research on it has been in the following 3 areas:
1. Ovulation –
The Chick is the ideal Model Organism for this as it has consistent and therefore predictable ovulation, readily accessible tissue in the organism and ideally sized follicles.
2. Toxicology –
The Chick is ideal for toxicology studies as it is more sensitive and gives more readily observed outcomes than other Model Organisms.
3. Ovarian Cancer –
The Chick is the only vertebrate model that can suddenly develop ovarian cancer that is genetically very similar to the disease in humans.
References:
Principles of Development 3rd Edition – Lewis Wolpert
Sourcebook of Models for Biomedical Research - P. Michael Conn
https://www.nih.gov/science/models/gallus/
Image courtesy of flickr under the creative commons license.