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.
The sex chromosomes are the X chromosome and the Y chromosome. In a man, both an X and a Y chromosome are present, giving an XY configuration. In a woman, there are two X chromosomes, giving an XX configuration. The X chromosome is therefore one of the two sex chromosomes that determines an individualâs gender.