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 chromosomes in the 23rd pair are called the SEX CHROMOSOMES. Sex chromosomes are labelled X or Y. Males normally have one copy of the X chromosome and one copy of the Y chromosome in each cell; it is the Y chromosome that determines maleness.