Genitals are developed from different rudimentary. So, uterus, tubes and a large part of the vagina develop from mullerova moves, ovary - from genital bands, located near embryonic kidneys, genitals - from the skin of the lower part of the body and of the urogenital sinus.
As you know, in different periods of embryo fetal development processes of differentiation, which is the final authority.
If in the process of formation and development of the fetus happen persistent violations in the differentiation of tissues, it can lead to deformities of the reproductive organs.
The question about the reasons of defects, female genital mutilation still. not solved. Sometimes naselenie and Bamyan separate parts of the urinary system can be explained by the delay of growth of tissue under the influence of those or other reasons. The reason for the delay of development can be inflammatory processes, transferred into the uterine and extrauterine life that caused bonding and consistent fusion of the walls of the cavity. In some cases the cause may be the metabolism of the embryo, in particular related to changes in the endocrine glands.