Male Reproduction

Ch. 28-1

Organs of the Male

• Testes – produce sperm and secrete hormones• System of ducts (epididymis, ductus deferens,

ejaculatory ducts, and urethra) – transports and stores sperm, assists in maturation

• Accessory sex glands (seminal vesicles, prostate, and bulbourethral glands) – adds fluid to semen

• Supporting structures – scrotum and penis – delivery and support

Organs

WORD BANK

Vas deferens

Scrotum

Urethra

Prostate

Epididymus

Bladder

Teste

Seminal Vesicle

Organs

• Scrotum (bag) – supporting structure for testes– Loose skin– Internally scrotum is divided into two sacs – one for

each testis– Location of testes is vital to sperm survival

• 2-3 degrees below normal body temperature• In cold – muscles pull the scrotum closer to the body to

keep sperm warm• In warm – opposite occurs

Organs

• Testes or testicles– Descend during 7th month of pregnancy– Where sperm are made during spermatogenesis

• Epididymis– Comma-shaped organ along the border of each

testis– Site of sperm maturation – sperm acquire motility

and ability to fertilize (14 days)– Stores sperm for up to several months

Organs

• Ductus deferens or vas deferens– Along border of epididymis and up around bladder– Push sperm during arousal toward the urethra– Also store sperm for several months

• Ejaculatory ducts– Eject sperm and seminal vesicle secretions before

release of semen• Urethra

– Passageway for urine and semen

Organs

• Seminal vesicles– Pouch like structures at base of bladder– Secrete alkaline fluid with fructose, clotting proteins,

prostaglandins• Alkaline fluid neutralizes female acidity in vagina• Fructose is for ATP production in sperm for their swim• Clotting proteins help semen coagulate after ejaculation

• Prostate– Doughnut shaped, golf ball sized organ– Secrete antibiotic for bacteria in urethra or vagina

Organs

• Bulbourethral glands or Cowper’s glands– Secrete alkaline fluid into urethra that protects

sperm from urine– Secretes mucus for lubrication of external penis

and urethra

Semen

• Mixture of sperm and seminal fluid• Seminal fluid from seminal vesicles, prostate,

bulbourethral glands– Contains 2.4-5 mL of fluid with 50-150 million sperm/mL– 20 million/mL or lower is considered infertile

• Slightly basic (7.2-7.7); milky appearance, sticky consistency

• Seminal fluid provides sperm with nutrients, transportation, protection

Penis

• Contains urethra and passageway for ejaculation of semen and urine

• Glans penis – head of penis• Erection – result of increased blood supply

to penile tissue

Penis

Penis

• Circumcision – removal of foreskin– Cleaner and decreases risk of infection or disease

• Vasectomy– Sterilization of males– Portion of ductus deferens is removed– Ducts are cut and tied with stitches– Sperm production continues, but sperm cannot

reach exterior of penis

Spermatogenesis

• Takes 65-75 days• Begins with spermatogonia

(stem cells)• Undergo meiosis – 4

spermatids• Spermiogenesis

– When spermatids become spermatozoa