This phase represents the initial phase of differentiation of reproductive tissues. The male Y chromosome in mammals contains genetic code that results in the production of '''testes-determining factor (TDF)''' which is responsible for causing the gonads to develop into testes. In the female fetus, TDF is not produced as there is no Y chromosome and therefore the gonads develop into ovaries. | This phase represents the initial phase of differentiation of reproductive tissues. The male Y chromosome in mammals contains genetic code that results in the production of '''testes-determining factor (TDF)''' which is responsible for causing the gonads to develop into testes. In the female fetus, TDF is not produced as there is no Y chromosome and therefore the gonads develop into ovaries. |