Male reproductive physiology and anatomy

Male reproductive physiology and anatomy encompass a highly coordinated system of organs, hormones, and cellular processes essential for sperm production (spermatogenesis), hormone synthesis (primarily testosterone), and delivery of sperm to the female reproductive tract. The key anatomical structures include the testes—paired, ovoid glands located within the scrotum—which serve dual endocrine and exocrine functions: Leydig cells produce testosterone under luteinizing hormone (LH) stimulation, while seminiferous tubules house germ cells undergoing spermatogenesis under the influence of both testosterone and follicle-stimulating hormone (FSH). Sperm mature and are stored in the epididymis, then travel through the vas deferens (ductus deferens), which joins the seminal vesicle duct to form the ejaculatory duct before emptying into the prostatic urethra. Accessory glands—including the seminal vesicles (contributing ~60% of seminal fluid volume and rich in fructose), prostate gland (providing proteolytic enzymes like prostate-specific antigen and citric acid), and bulbourethral (Cowper’s) glands (secreting a clear, alkaline mucus that lubricates and neutralizes residual acidity in the urethra)—collectively produce seminal plasma, which nourishes and protects sperm. Hormonally, the hypothalamic–pituitary–gonadal (HPG) axis tightly regulates reproductive function: gonadotropin-releasing hormone (GnRH) from the hypothalamus stimulates pituitary secretion of LH and FSH; LH acts on Leydig cells to drive testosterone synthesis; and FSH supports Sertoli cell function, which is critical for spermatogenesis and spermiation. This integrated system ensures fertility, secondary sexual development, libido, and overall metabolic and bone health in males.