Why do the tissues that are present in all embryos decide to

Why do the tissues that are present in all embryos decide to develop into female reproductive organs or male reproductive organs? What factors go into determining this? What then develops once that determination is made? 100 words or more please

Solution

Humans have two sex chromosomes – the X chromosome and the Y chromosome. Females carry two copies of the X chromosome (XX) and males carry one of each (XY). Thus, Y chromosome is the sex-determining chromosome in humans. The development of testes occurs under the influence of androgens, which need the presence of Y-chromosome.

The SRY (Sex Determining Region Y) gene encodes a protein known as Sex determining Region Y protein. This protein determines the development of sexual characteristics in a fetus. SRY gene is present on Y chromosome.

The SRY protein controls the expression of particular genes and triggers the process of male gonads development. Thus, this process inhibits the development of female gonads and female reproductive structures while promoting the development of male reproductive structures.

The presence of androgens trigger the development of male accessory sex organs. Estrogens do not determine the development of accessory sex organs either in males or females.

The accessory organs of males are derived from the wolffian (mesonephric) ducts. In males, the miillerian inhibition factor (MIF) is secreted by the semniferous tubules. The MIF is a polypeptide, which causes regression of the mullerian duct by the 60^th day. The experimental removal of testes resulted in the development of mullerian ducts into female accessory organs, while the wilffian ducts are regressed.

Thus, the female accessory sex organs develop due to the absence of testes but not due the presence of ovaries.