The Male Reproductive System

The Male Reproductive System

• The main task of the reproductive system is the production of reproductive cells and the secretion of hormones
• The endocrine glands and the nervous system have a direct influence on the work of the reproductive system

Testis

• Egg-shaped, 5 cm long, 3 cm wide, and 2.5 cm thick, each weighing 10-15 grams
• Hangs in the scrotum
• Produces sperm and contains endocrine cells that secrete hormones like testosterone
• Testosterone drives male reproductive physiology, is important for spermatogenesis, sexual differentiation, and control of gonadotropin secretion in the pituitary

Scrotum

• A sac of skin and superficial fascia that hangs outside the abdominopelvic cavity at the root of the penis
• Contains paired testicles separated by a midline septum
• External positioning keeps the testes 3°C lower than core body temperature

Seminiferous Tubules

• Contain Sertoli cells, spermatogonia, primary spermatocytes, secondary spermatocytes, and spermatids
• Sertoli cells provide support and nutrition for developing sperm
• Interstitial cells (Leydig cells) secrete testosterone

Spermatogenesis

• Occurs in three phases: Golgi, acrosomal, and maturation
• Results in the formation of spermatozoa

Sperm

• Have three major regions: head, midpiece, and tail
• Head contains DNA and has a helmet-like acrosome containing hydrolytic enzymes
• Midpiece contains mitochondria spiraled around the tail filaments
• Tail is a typical flagellum produced by a centriole

Epididymis

• Has three functions: monitors and adjusts fluid produced by seminiferous tubules, recycles damaged spermatozoa, and stores and protects spermatozoa
• Divided into head, body, and tail
• Head receives spermatozoa from efferent ductules, body is where maturation occurs, and tail is the primary storage location of spermatozoa

Ductus Epididymis

• Begins at the tail of the epididymis and forms the vas deferens
• Has a pseudostratified columnar epithelium with stereocilia (microvilli) and a layer of smooth muscle

Vas Deferens (Ductus Deferens)

• Is 40-45 cm long and begins at the tail of the epididymis
• Ascends through the inguinal canal and curves inferiorly along the urinary bladder
• Lumen enlarges into an ampulla and empties into the prostatic urethra
• Wall contains a thick layer of smooth muscle

Ejaculatory Duct

• A short passageway (2 cm) at the junction of the ampulla and seminal gland duct
• Penetrates the wall of the prostate gland and empties into the urethra

Accessory Genital Glands

• Seminal vesicle and prostate gland
• Produce alkaline mucus prior to ejaculation that neutralizes traces of acidic urine in the urethra

Seminal Vesicle

• A tubular gland that is about 15 cm long with short side branches from the body
• Produces about 60% of semen volume
• Secretes fructose, fibrinogen, and prostaglandins

Prostate Gland

• A small, muscular organ, about 4 cm in diameter
• Encircles the proximal portion of the urethra
• Consists of 30-50 compound tubuloalveolar glands
• Surrounded by smooth muscle fibers and produces alkaline mucus