Definition: A Y-chromosome is the sex chromosome found only in males. The two types of sex chromosomes, X and Y, determine the sex of an embryo. Women have two X chromosomes and men have an X and a Y chromosome. Because of this, the sex of the child is determined by which chromosome the male passes down. At approximately the eighth week of prenatal development, the Y-chromosome triggers the development of male sex organs.
What Is a Y-Chromosome?
By Kendra Van Wagner, About.com
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