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. 1. chromosome-a threadlike strand of DNA in the cell nucleus that carries the genes in a linear order; humans have 22 chromosome pairs plus two sex chromosomes. cell nucleus, karyon, nucleus-a part of the cell containing DNA and RNA and responsible for growth and reproduction.