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Human Anatomy. Male Reproductive System. Functions of ♂and ♀. Production of sex cells (1 ° sex organ) Delivery of sex cells to place of fertilization ♀ -- development of embryo/fetus. Overview of Male. Testes (Testis, sng.). 1 ° sex organ production of sperm Secretion of testosterone
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Human Anatomy Male Reproductive System
Functions of ♂and ♀ • Production of sex cells (1° sex organ) • Delivery of sex cells to place of fertilization • ♀ -- development of embryo/fetus
Testes (Testis, sng.) • 1° sex organ • production of sperm • Secretion of testosterone • Suspended within the scrotum • Scrotum is a pouch of skin with a thin muscular wall • Testes first appear at 7 weeks next to kidneys • Testes don’t descend into the scrotum until about 8 months of fetal age
Cryptorchidism • Failure of one or both testes to descend into the scrotum prior to birth • 3% of full term males • 30% of premature males • Most descend w/in a few weeks after birth • Sterility occurs if not descended • Usually removed by puberty -- cancerous
Scrotum • Wall comprised of smooth muscle – the Dartos • Cremaster m. (skeletal m.) attached to dermis • Temperature control of testes • Sperm development occurs at 35° • Sperm will not develop at body temperature.
Testes Comprised of hollow tubing – seminiferous tubules This is where sperm develop
Seminiferous Tubules • Each testis contains ~ 800 seminiferous tubules. • Each tubule is about 2.5 ft. in length. • Each testis contains ~ one half mile of tubing. • Sperm maturation takes about 9 weeks.
Structure of Sperm • Sperm cells consist of: • Head – containing the nucleus (male DNA) 2. Middle piece and neck – contains large spiral mitochondrion 3. Tail – corkscrew motion to propel sperm 4. Acrosome – membrane bound bag of enzymes covering head.
Testosterone Production Occurs in cells between seminiferous tubule. Interstitial cells or Cells of Leydig
Epididymus Posterior Superior Border of Testis
Epididymis • Located on posterior/superior border of testes • Acts as recycling center for damaged sperm • Stores sperm for up to 2 months • Allows sperm to be fully functional -- capacitation
Ductus (vas) Deferens • About 16 in. long • Begins at end of epididymis • Ascends into the abdominal cavity by piercing the anterior muscles • Courses around posterior surface of bladder • And then into the prostate gland
Ductus (vas) Deferens Vas wall is mostly smooth muscle. Contraction propels sperm to utethra
Three Glands • Secretions that mix with sperm. • Sperm + secretions = semen (ejaculate) • Typical ejaculate is about 2 – 5 ml (about 1 teaspoon containing 500 million sperm) • 3 glands are: • Seminal vesicles • Prostate gland • Bulbourethral glands
1. Seminal Vesicles Posterior surface of the urinary bladder 60% of total semen volume Contains large amount of fructose Seminal vesicle fuses with vas deferens to form ejaculatory duct
Ejaculatory Duct Starts where vas fuses with 1st gland – seminal vesicle Ejaculatory duct enters prostate gland
Prostate and Urethra Ejaculatory duct enters urethra
2. Prostate Gland Contributes app. 25% total semen Volume May prevent Infections of Urinary tract
3 Portions of the Urethra • Prostatic – within the prostate gland • Membranous – passes through the pelvic muscles to enter the penis (shortest) • Penile – courses the entire span of the penile shaft (longest)
3. Bulbourethral Glands Secretes into membranous urethra –alkaline mucous
Penis Glans Shaft
Body (shaft) • Consists of 3 parallel columns of erectile tissue • 2 corpora cavernosa • 1 corpos spongiosum • Urethra runs through corpus spongiosum
Glans • Distal expansion of the corpus spongiosum • Opening of the urethra -- external urethral meatus