Male Reproductive System

Male Reproductive SystemLabeling

Testis Epididymis

Scrotum Vas deferens

Prostate Seminal vesicle

Urinary bladder

Rectum

Penis Cowper’s Glands

Urethra

Testes• Testes (2 of them)

– Male gonads– Seminiferous tubules

• Site of sperm formation in the testes• FSH stimulates sperm production

– Leydig cells (interstitial cells)• Scattered among the seminiferous

tubules• Produce testosterone• LH stimulates testosterone

production– Epididymis

• Tube in the testes where sperm gain mobility

• Suspended in the scrotum

Urethra• Tube that extends

from the bladder, through the penis, to the outside of the body

• Carries semen and urine

• 5-7 inches long in male

Penis• External male reproductive organ• Glans penis - enlarged structure on the

end of the penis– This is covered by the prepuce or foreskin– The foreskin is removed in a procedure called

circumcision

• Penis is made of spongy, erectile tissue– During sexual arousal, the erectile tissue

fills with blood from the arteries, causing an erection

• Functions– male organ of copulation/intercourse– Elimination of urine from the bladder

Ejaculation

• The male gonads, or testes, consist of highly coiled tubes surrounded by connective tissue

• Sperm form in these seminiferous tubules

• From the seminiferous tubules of a testis, sperm pass into the coiled tubules of the epididymis

• During ejaculation, sperm are propelled through the muscular vas deferens and the ejaculatory duct, and then exit the penis through the urethra

Semen

• Three sets of accessory glands add secretions to the semen, the fluid that is ejaculated– The two seminal vesicles

contribute about 60% of the total volume of semen

– The prostate gland secretes its thin milky fluid containing enzymes and sperm nourishment directly into the urethra

– The Cowper’s gland secretes a clear mucus before ejaculation that neutralizes acidic urine remaining in the urethra

The Male Hormone Pattern

Reproductive Hormones

• Androgen: Testosterone– Primary sex characteristics

• development of the vas deferens and other ducts• development of the external reproductive structures• sperm production

– Secondary sex characteristics

• Deeper voice• Axillary and pubic hair• Chest and facial hair• Lengthen bones• Increased size of testes for sperm production

Reproductive HormonesGonadotropic Hormones◦ Released from the Anterior Pituitary Gland

Follicle-Stimulating Hormone (FSH) stimulates production of sperm

Luteinizing Hormone (LH) stimulates secretion of testosterone

The Male Pattern

The Male Pattern

• The male hormone pattern is continuous.• The principle male sex hormones are

androgens specifically testosterone.• Gonadotropin-Releasing Hormone (GnRH)– Produced by the hypothalamus– Regulates FSH and LH levels– Controlled by negative feedback from FSH and LH

Copyright Pearson Prentice Hall

Sperm Production Regulation

Spermatogenesis

• Process of sperm production• Continuous process that begins at puberty and

continues through life• LH induces Leydig cells to produce

testosterone• Together with FSH, testoterone stimulates

sperm production in the seminiferous tubules.

Testicular Cancer

Cancer of the testiclesFrequent in men 20-35Highly malignant and

spreads quicklyTreatment◦ Orchiectomy, radiation

ACS◦ American Cancer Society◦ Recommends STE◦ Self testicular exam