Basics of Vulval Embryology, Anatomy and Physiology

Abstract

A basic knowledge of the events in the embryogenesis and organogenesis of the female reproductive tract is important in order to understand the congenital abnormalities that may arise. The female genital tract is closely linked to the development of both the urinary and terminal part of the gastrointestinal tracts, explaining why some congenital abnormalities of the female reproductive tract may be found in association with anomalies of the urinary and gastrointestinal systems.

The Normal Vulva, Vulvar Examination, and Evaluation Tools

“…The intracellular concentration of glycogen increases, and its metabolism by lactobacilli causes vaginal fluid to become acidic. 1,2,5,6 Menstruation appears about 4 years after these changes begin. The mean age of menarche worldwide is between 12 and 13 years, the differences between races are minor.…”

“…At the 8th gestational week, the female embryo's gonads start differentiation toward ovaries, but the external genitalia are still indifferent, and both mesonephric (wolffian) and paramesonephric (mullerian) ducts are present. [2][3][4] In the female fetus, the mesonephric ducts will degenerate in the next weeks due to lack of anti-mullerian hormone. In the absence of testosterone, the paramesonephric ducts develop and combine partly to a Y-shaped structure: its distal end makes contact with the posterior wall of the urogenital sinus.…”

“…8 The labia minora lack subcutaneous fat, and contain erectile tissue comprised of thick connective tissue rich in small blood vessels. 2,3 The Vestibule The vestibule extends anteroposterior from the frenulum of the clitoris to the fourchette, and laterally to the labium minus on each side. The vestibule is covered by endodermal-originated mucosa, as the inner third of the labia minora.…”

“…The combined ducts will eventually form the upper vagina and uterus, whereas the divided parts develop into the fallopian tubes. 2,4 The lower part of the vagina and the external genitalia originate from the genital tubercle, urogenital folds, and urogenital swellings, which surround the cloacal membrane at the ventral side of the embryo. In the 5th week of embryonic life, a septum divides the cloaca into a ventral portion, the urogenital sinus, and a dorsal anorectal canal.…”

“…They are the most lateral structures in the vulva, separated from the inner thighs by the genitocrural folds. 2 The cutaneous epithelium covering the mons pubis and labia majora is derived from the embryonic ectoderm. It exhibits a keratinized, stratified, squamous structure with sweat gland, sebaceous glands, and hair follicles.…”