The stages of<unk>  duct development in the human embryo and its associated outcomes during normal and impaired development. The human female reproductive system consists of the gonads, external genitalia and the<unk>  duct system. Initially in the embryo, both the Wolffian (mesonephric) and<unk>  (paramesonephric) ducts are present, where development of the Wolffian ducts give rise to the male reproductive tract and development of the<unk>  ducts give rise to the female reproductive tract. These ducts are identical until approximately week 6 of embryonic development. In males, the sex-determining region Y (SRY) gene on the Y chromosome suppresses<unk>  duct development, by initiating the production of anti-Mullerian hormone by the Sertoli cells of the testis. The<unk>  ducts only develop in the absence of anti-Mullerian hormone, where the Wolffian ducts regress. Development of the female reproductive tract begins at approximately week 8 of embryonic development, and development of the<unk>  duct system is typically complete by the end of the first trimester. The<unk>  ducts develop to give rise to the fallopian tubes, uterus, cervix and upper two-thirds of the vagina. The ovaries are not part of the<unk>  system and arise from primordial germ cells, which develop at the gonadal ridge. The formation of the female reproductive tract via the<unk>  ducts has 3 distinct stages. An array of<unk>  can occur if any of these processes are arrested or impaired. The first stage of<unk>  duct development is organogenesis, where both<unk>  ducts are formed. If the formation of the<unk>  ducts is impaired or does not occur, this can give rise to uterine, cervical and/or vaginal hypoplasia or agenesis.<unk>  agenesis, also known as the Mayer–Rokitansky–Kuster–Hauser (MRKH) syndrome, results in the congenital absence of the vagina or uterus. Women with MRKH syndrome commonly present with primary amenorrhea, where menstruation does not occur by the age of 16. In the first stage of development, it is also possible for only one<unk>  duct to develop, giving rise to a single uterine horn (unicornuate uterus). Unicornuate uteri commonly develop on the right side, although the reason for this preference remains elusive. The second stage of<unk>  duct development involves the fusion of the inferior portion of the ducts to form the uterus, cervix and upper two-thirds of the vagina. The superior part of the<unk>  ducts do not fuse and form the left and right fallopian tubes. Disruptions to this stage of development can result in didelphys or bicornuate uteri<unk> . In both didelphys and bicornuate uteri, the non-fusion of the<unk>  ducts results in two distinct uterine cavities. The third and final stage of<unk>  duct development is septal resorption. After the lower<unk>  ducts fuse, a central septum is left behind, and this partition must be eliminated to give rise to a single uterine cavity, cervical canal and vaginal canal. Defects in septal resorption may produce a septate uterus or arcuate uterus, where the septum divides the uterine cavity. More than 50% of women with reported<unk>  have septate uteri. It is common for other developmental defects to occur in conjunction with<unk> , including renal, skeletal, auditory and cardiac abnormalities.
Mullerian anomalies
Sex chromosome anomalies
Ovarian disease
Lactational amenorrhea
Sexual anomalies
Tubal factor infertility
Blighted ovum
Female infertility