Anatomy of the vulva
Miranda A. Farage, Howard I. Maibach in The Vulva, 2017
Early in the fifth week of embryonic life, the cloaca is divided by the urorectal septum, which gives rise to the perineum. Folds of tissue form on either side of the cloaca: the anterior folds are urogenital and the posterior folds are anal. The anterior folds meet at the midline to form the genital tubercle. The genital tubercle enlarges. In the male embryo, under the influence of androgens, the genital tubercle becomes the penis; in the female embryo, growth slows and it becomes the clitoris. On either side of the tubercle, the urogenital folds form the labia minora. In the indifferent stage, the labioscrotal swellings develop on either side of the urogenital folds. In the male embryo, under the influence of androgens, they differentiate into the scrotum; in the female, lacking androgenic stimulation, they remain largely unfused to become the labia majora. The definitive urogenital sinus gives rise to the vaginal vestibule, into which the urethra, vagina, and greater vestibular glands open.
Embryology
Anthony R. Mundy, John M. Fitzpatrick, David E. Neal, Nicholas J. R. George in The Scientific Basis of Urology, 2010
As already described, the fetal testis originates from the interaction of primordial germ cells, with the mesenchyme of the genital ridge and tubular mesonephric duct derivatives. Testicular descent occurs in two phases. The first stage occurs in response to exposure to MIS, the second being stimulated by testosterone. Between weeks 8 and 15, the cord-like gubernaculum extending down from the testis enlarges at its distal end in the region of the labioscrotal swellings (Fig. 15A). Because the length of the gubernaculum remains relatively fixed during a period of active fetal growth, this has the effect of anchoring the testis in the region of the future inguinal canal (Fig. 15B). The second, more active, phase of testicular descent occurs around 25 to 30 weeks of gestation when testosterone causes the gubernaculum to shrink and contract, thus guiding the testis down the inguinal canal into its final scrotal position (Fig. 15C) (18). On its route of descent, the testis is preceded by a sac-like protrusion of peritoneum, the processus vaginalis, which normally closes spontaneously prior to delivery or in the early months of life.
Surgical treatment of disorders of sexual development
Mark Davenport, James D. Geiger, Nigel J. Hall, Steven S. Rothenberg in Operative Pediatric Surgery, 2020
Most girls with 46,XX DSD have labioscrotal swellings that are anterior in relation to the vagina than normal labia majora. Significant skin rugation may be present as well. To move this labioscrotal skin posteriorly, “Y”-shaped incisions are outlined with an extension posterior to the swellings. The scrotal flaps are cautiously defatted and moved posteriorly, beside the introitus, as bilateral Y–V advancements (Figure 80.9). The medial aspects of these skin flaps are then sutured to the lateral edges of the prepucial skin flaps mobilized during clitoroplasty (now labia minora) (Figure 80.10). The result is an anatomically correct positioning of the labia minora and majora posteriorly, beside the introitus, rather than anteriolaterally.
Accessory Scrotum
Published in Fetal and Pediatric Pathology, 2020
Fatma Fitouri, Nesrine Chebil, Sabrine Ben Ammar, Sondes Sahli, Mourad Hamzaoui
Accessory scrotum describes the anomalous position of scrotal tissue and can be either a mid-perineum type or a lateral type [2]. Some authors have suggested that the failure of movement of the labioscrotal swelling to the midline could be responsible for the occurrence of accessory scrotum. Other authors think that abnormal division of the labioscrotal swelling could be the cause [3]. Absence of other organ malformations suggests that the causative factor may not have adverse effects on other organ systems undergoing differentiation at the same time [4]. The treatment is simple surgical excision. The accessory scrotum is different from the ectopic scrotum. The ectopic scrotum contains a testis, requiring repositioning or excising the scrotum with preservation of the testis [5]. The accessory scrotum which does not contain a testis is treated by simple excision after verification that there is no testis present [2].
Related Knowledge Centers
- Genital Tubercle
- Labia Minora
- Embryo
- Scrotum
- Mons Pubis
- Sex Organ
- Sexual Differentiation
- Labia Majora
- Development of The Reproductive System