Embryology of The Female Genital Tract Basim Abu-Rafea, MD, FRCSC, FACOG Assistant Professor & Consultant Obstetrics & Gynecology Reproductive Endocrinology & Infertility Advanced Minimally Invasive Gynecologic Surgery Department of Obstetrics & Gynecology King Khalid University Hospital King Saud University

Gonads At approximately 5 weeks of gestation, the gonads are structurally consolidated coelomic prominences overlying the mesonephros, forming the gonadal ridges. At this point, the gonad is morphologically indistinguishable as a primordial testis or ovary.

Gonads

Testes The factor that determines whether the indifferent gonad will become a testis is called, the testes-determining factor (TDF), a product of a gene located on the Y chromosome. The male phenotype is dependent on the products (antimüllerian hormone and testosterone) of the fetal testes which are secreated from Sertoli cells & Leydig cells.

Ovary Ovarian differentiation are reflected in the rapid mitotic multiplication of germ cells, reaching 6–7 million oogonia by 16–20 weeks.

Female Genital Tract In the absence of AMH, the fetus will develop fallopian tubes, uterus, and upper vagina from the paramesonephric ducts (the müllerian ducts).

Female Genital Tract Canalization to create the uterine cavity, the cervical canal, and the vagina is complete by the 22nd week of gestation. By the 20th week of pregnancy, the uterine mucosa is fully differentiated into the endometrium.

Anomalies Anomalies can originate in the failure of the müllerian ducts to fuse in the midline to connect with the urogenital sinus to create the appropriate lumen in the upper vagina and uterus by resorption of the central vaginal cells and the septum between the fused müllerian ducts.

Abnormal müllerian differentiation frequently is associated with urologic malformations.

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