1 Colored Egg Layer Chickens. The Araucana is a pure breed of chicken originating in Chile. 2  Ameraucana chickens were developed in the 1970âs in the United States from Araucanas. They were developed as a practical barnyard fowl that laid pastel shelled eggs, but without some of the limiting genetic factors related to rumplessness and tufts.
sex chromosome. a chromosome, differing in shape or function from other chromosomes, that determines the sex of an individual.
noun, plural: sex chromosomes. A type of chromosome in the genome that is involved in the determination of the sex as well as the development of sexual characteristics in an organism. It occurs in pairs in somatic cells while singly in sex cells (gametes).