Accessory reproductive organs: ducts, glands, and external genitalia.
Anatomy of the Male Reproductive System ○ Sperm-producing testes lie within scrotum. The sperm then travels through the epididymis, the ductus (vans) deferens, the ejaculatory duct, and finally the urethra which opens to outside at the tip of the penis. ○ Accessory sex glands that empty their secretions into the ducts during ejaculation are the seminal glands, prostate, and bulbo-urethral glands. The Scrotum § A sac of skin and superficial fascia that hangs outside abdominopelvic cavity. Contains testes. Midline septum divides scrotum, providing compartments. § Viable sperm can't be produced at body temp (37 degrees celcius), outside the body provides temp about 3 degrees lower. § The dartos muscle wrinkles scrotal skin. The cremaster muscles elevate the testes. The Testes § Each testis is surrounded by 2 tunics. The outer tunic is the 2-layered tunica vaginalis, derived from outpocketing of peritoneum. Deep to this is the tunica albuginea, the fibrous capsule of the testis. § Septa extending from tunica albuginea divide testes into about 250 lobules, each contains one to four tightly coiled seminiferous tubules (sperm factories), thick stratified epithelium surrounding fluid containing lumen. § The epithelium has spheroid spermatogenic cell, embedded in larger columnar cells called sustentocytes, supporting cells that play several roles in sperm formation. § Surrounding each S tubule are 3-5 layers of smooth muscle-like myoid cells. By contracting, they squeeze sperm & testicular fluid through tubules & out of testes. § The S tubules of each lobule converge to form straight tubule that conveys sperm to rete testis. Then they leave testis through efferent ductules and enter epididymis. They are stored there until ejaculation. § In soft connective tissue surrounding S tubules are interstitial endocrine cells (Leydig cells). Produce androgens (esp. testosterone) and secrete into surrounding IF. § Testicular arteries supply testes. Testicular veins drain testes and form network called pampiniform venous plexus, which help keep testes at their cool homeostatic temp. § A connective tissue sheathe encloses nerve fibers, blood vessels, and lymphatics, and collectively they make up spermatic cord, which passes through inguinal canal. § Homeostatic Imbalance: Testicular cancer most common cancer in men 15-35. History of mumps or orchitis (inflammation of testes) & substantial maternal exposure to environmental toxins increase risk. Most important risk factor is cryptorchidism: nondescendence of testes. The Male Perineum § Suspends the scrotum & contains root of penis and anus. The Penis § Copulatory organ. Penis & scrotum are external genitalia. § Ends in an enlarged tip called the glans penis. Foreskin = prepuce. § Internally, contains the spongy urethra and 3 long cylindrical bodies (corpora) of erectile tissue and it is riddled with vascular spaces. During arousal, vascular spaces fill w/ blood, causing penis to enlarge and become rigid, called erection. § The midventral erectile body, called corpus spongiosum surround urethra. It expands distally to form glans penis and proximally to form bulb of the penis. Sheetlike bulbospongiosus muscle covers bulb externally. § Paired dorsal erectile bodies, called corpora cavernosa, make up most of penis and are bound by tunica albuginea. Proximal ends form crura of the penis. Each crus is surrounded by ischiocavernous muscle. The Male Duct System The Epididymis □ Its head contains efferent ductules. □ Most of it consists of highly coiled duct of epididymis. Some pseudostratified columnar epithelial cells of