Anatomy
What is the function of the prostate and seminal vesicles?
The prostate produces a secretion forming 15-30% of the ejaculate volume. The secretion is fluid, colourless, of acidic reaction (pH 6.4), it contains zinc, citric acid, prostaglandins, polyamines – spermin and spermidin, immunoglobulins, acid phosphatase and proteases. Zinc influences the metabolism of testosterone in the prostate; besides, it accumulates as a complex on the spermatic cell wall. Citric acid in the form of citrates functions as a buffer, prostaglandins stimulate uterine muscles and thus contribute to the sperm transport, spermin influences the motility of sperm and their capacity to fertilize the egg, proteases cause liquification of the ejaculate.
For its growth and correct functioning, the prostate needs male sexual hormones or androgens, of them namely testosterone. Ninety % of androgens in the male organism are represented by testosterone, which is formed in the Leydig cells of testes, 10% by dehydroepiandrosterone and androstendione produced by adrenal glands. Ninety-eight % of testosterone is bound to the proteins of blood plasma (sex hormone-binding globulin – SHBG). Enzyme 5-alpha-reductase converts testosterone to dihydrotestosterone, which is bound to a specific cytoplasmic androgen receptor. Thus formed androgen-receptor complex is bound to specific sites on a DNA molecule in the cell nucleus. After transcription of androgen-dependent genes, specific proteins are generated and act on the stroma and glandular cells, maintaining the prostate activities.
The seminal vesicle is a geminate accessory gland of the male genital system, ensuring by its secretion the main volume of the ejaculate. The secretion contains fructose, prostaglandins and a number of proteins. Its production is dependent on testosterone.