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 7 th 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 mL of fluid with million sperm/mL – 20 million/mL or lower is considered infertile Slightly basic ( ); 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

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 days Begins with spermatogonia (stem cells) Undergo meiosis – 4 spermatids Spermiogenesis – When spermatids become spermatozoa