Physiology of the Male Accessory Sex Structures: The Prostate Gland, Seminal Vesicles, and Bulbourethral Glands

This chapter focuses on the physiology of the male accessory sex organs including the prostate gland, seminal vesicles, and bulbourethral gland. The prostate gland, seminal vesicles, and bulbourethral gland are vital organs of the male reproductive system that are responsive to androgens whose function is intimately linked to that of the male gonads or testes; they provide the constituents of seminal plasma in the semen. Prostate development begins in the human during the 11th to 12th week of gestation as five pairs of epithelial buds emerge from the urethral portion of the urogenital sinus (UGS), above and below the entrance of the mesonephric ducts. The main function of the prostate gland is to contribute secretions to the ejaculate. The development of other male accessory sex organ seminal vesicles in the male human begins at approximately 12 weeks of fetal age from the mesonephric or Wolffian duct, as does the development of the epididymis and the vas deferens. Buds that form the seminal vesicles emerge as dorsolateral swellings or dilations of the mesonephric duct proximal to the region where it joins the urethra. At maturity, when growth and cyto differentiation are complete, the seminal vesicle consists of a highly folded glandular epithelium with tall columnar luminal secretory cells and a discontinuous layer of basal cells, surrounded by a stromal layer of smooth muscle. The bulbourethral glands, also known as Cowper's glands, are present in most mammals. This pair of glands produces secretions that empty into the bulbous urethra and contribute to the seminal plasma.