Male Reproductive Physiology - Lecture 1

Male Reproductive Physiology - Lecture 1

• The male reproductive system has two main components: the gonads (testes) and accessory glands and ducts.
• The system includes the testes, epididymis, vas deferens, ejaculatory duct, urethra, penis, and scrotum.
• The vas deferens is a thick, muscular tube bundled with connective tissue, blood vessels, and nerves to form the spermatic cord.
• Accessory sex glands include seminal vesicles, prostate, and bulbourethral glands (Cowper's glands).
• The main function of the gonads is spermatogenesis (sperm production) and sex hormone production, which support reproduction.
• The ducts are responsible for transporting sperm and semen. The epididymis aids in sperm storage, maturation, and motility acquisition.
• Accessory sex glands produce seminal plasma with components like fructose, citric acid, calcium, prostaglandins, and fibrinogen.
• The penis is the male organ of copulation.

Male Reproductive Physiology - Structure of Testes

• Testes are paired oval structures (approximately 4-5 cm in length).
• They are housed in the scrotum, which helps maintain temperature 2-4°C below core body temperature for optimal sperm production.
• Two layers surround the testes: the outer tunica vaginalis (a serous membrane) and the inner tunica albuginea (a dense connective tissue layer).
• The tunica albuginea divides the testis into 300-400 lobules containing seminiferous tubules.
• Seminiferous tubules are coiled, each averaging more than half a meter long.

Male Reproductive Physiology - Spermatogenesis

• Spermatogenesis occurs in seminiferous tubules during active sexual life, stimulated by GnRH, FSH, and LH.
• Spermatogonia undergo mitotic division and differentiation at puberty forming primary spermatocytes.
• Primary spermatocytes undergo meiotic division, reducing the chromosome number to 23.
• Resultant spermatids mature to spermatozoa (sperm) through spermiogenesis within the Sertoli cells.
• Sertoli cells are crucial to sperm production, supplying nutrients and other important factors.
• A blood-testis barrier created by tight junctions in Sertoli cells isolates developing germ cells and prevents an immune response.
• Leydig (interstitial) cells produce testosterone, essential for spermatogenesis.
• One spermatogenesis cycle takes 64-72 days.
• Acidic medium and high temperatures can harm sperm function.

Male Reproductive Physiology - Structure of Sperm

• Sperm structure consists of a head, midpiece, and tail.
• Sperm head contains the nucleus, acrosome (cap), and centriole.
• The midpiece houses mitochondria, supplying energy for motility.
• The tail (flagellum) allows movement using the flagellum's back-and-forth movement.
• Acrosome contains enzymes (e.g., hyaluronidase) crucial for fertilization.
• Upon ejaculation, sperm undergo capacitation within the female reproductive tract, increasing motility and readiness for fertilization.

Male Reproductive Physiology - Contraception

• Contraception methods prevent pregnancy through various mechanisms.
• Methods include hormonal disruption (e.g., oral contraceptives), blockage of passageways (e.g., barrier methods), or preventing implantation.
• Intrauterine devices (IUDs) and surgical methods (e.g., vasectomy, salpingectomy) are also options.
• Considerations include efficacy, safety, acceptability, availability, pregnancy plans, health status, side effects, and risks, during counseling.
• Methods are available for both females and males