Male Reproductive

System

Reproductive Anatomy of the Human Male. External:

- penis - scrotum

Internal: - gonads- accessory sex glands and ducts.

Human reproduction involves intricate anatomy and complex behavior

Male Reproductive System

Testis

Male Reproductive System

External structure of the penis:

glans penis

prepuce (foreskin)

Testis are the male gonads. seminiferous tubules- form sperm Leydig cells (interstitial cells)- produce

androgens (ex. Testosterone, ABP).

Testes are located in the scrotum, outside the body cavity. This keeps testicular temperature cooler

than the body cavity. The testes develop in the body cavity and

descend into the scrotum just before birth.

Sperm Pathway

Prostatic urethra

Membranous urethra

Semen Seminal fluid is thick, yellowish, and

alkaline. It contains mucus, fructose, a coagulating

enzyme, ascorbic acid, and prostaglandins.

Accessory glands:

1.seminal vesicle

2.prostate gland

3.bulbourethral gland

Seminal Vesicle

Seminal vesicle:• A pair of glands that secrete a liquid

component of semen into the vas deferens. • Secretion is alkaline• Contains fructose, asorbic acid, coagulating

enzyme, prostaglandin

Prostate gland:• Location- surrounds and opens into the urethra where it

leaves the bladder. • Secretion- slightly alkaline fluid that activates the sperm

and prevents them from sticking together Prostate problems are common in males over 40. Prostate cancer is one of the most common cancers

in men.

Prostate

Bulbourethral gland (Cowper’s gland): • Location- paired glands that lie beneath the prostate• Secretion- a thick, clear alkaline mucous that drains into

the membranous urethra. • Function- It acts to wash residual urine out of the urethra

when ejaculating semen-- raises pH; neutralizes acidity of urine.

Bulbourethral gland

Spermatogenesis

Mature Spermatozoa

tail

mitochondria

nucleus

acrosomehead

spermatogonium

1º spermatocyte

2º spermatocyte

spermatidsSertoli cell

spermatozoa

Seminiferous Tubules

Seminiferous Tubules

Sperm Maturation & Development

Hormones Involved in Spermatogenesis

• Gonadotropin Releasing Hormone (GnRH)• Follicle Stimulating Hormone (FSH)• Interstitial Cell Stimulating Hormone (ICSH=LH)• Testosterone• Inhibin• ABP

Feedback Inhibition

InhibinInhibinActs on anterior pituitaryActs on anterior pituitaryInhibits FSH productionInhibits FSH production

TestosteroneTestosteroneActs on hypothalamusActs on hypothalamusInhibits GnRH productionInhibits GnRH production

Hormonal Control of Spermatogenesis

Some Other Effects of Testosterone

muscle and bone growthmuscle and bone growthfacial and pubic hair growthfacial and pubic hair growth

thickening of vocal cordsthickening of vocal cordsgrowth of pharyngeal cartilagegrowth of pharyngeal cartilage

hair follicle effectshair follicle effectsstimulates sebaceous glandsstimulates sebaceous glands

Increased BMRIncreased BMR

Vasectomy

Female Female Reproductive SystemReproductive System

cervix

vagina

fimbriae

uterine tube

ovary

uterus

bladder

urethra

clitoris

l. minora

l. majora

Female Reproductive System

Internal reproductive:

• Vagina• Cervix• Fallopian tube

(uterian tube/oviducts)• Fimbrae• Ovary• Uterus

- Endometrium- Myometrium- Perimetrium

cervixvagina

fimbriae

uterine tube

ovary

uterus

endometrium

myometrium

perimetrium

Fimbrae & Fallopian Tube

Oogenesis in the Ovary

OogenesisOvary- contains 400,000 oocytes; release

about 500 in a lifetime• Ovary- under influence of FSH. The

follicles mature every 28 days• Primary follicle produces estrogens• And primary oocyte completes its 1st

division produces 2ndary oocyte and polar body

Oogenesis• Aprox 1/2 way through the 28 day cycle the

follicle reaches the mature Vesticular or Graffian follicle stage.

Oogenesis

• Estrogen levels rise and release LH and FSH and triggers ovulation.

Oogenesis• The 2ndary oocyte travels down the uterine

tube to the uterus.• If fertilized by sperm, it will produce a zygote

Ovum in uterine tube

Ectopic Pregnancy

Oogenesis

Hormones Involved in the Female Reproductive Cycle

Gonadotropin Releasing Hormone (GnRH)Gonadotropin Releasing Hormone (GnRH)Follicle Stimulating Hormone (FSH)Follicle Stimulating Hormone (FSH)

Luteinizing Hormone (LH)Luteinizing Hormone (LH)EstrogenEstrogen

ProgesteroneProgesteroneInhibinInhibinRelaxinRelaxin

The Uterine Cycle

Hormone Fluctuation

Some Other Effects of Some Other Effects of EstrogenEstrogen

• breast development• external genitalia growth• bone growth• fat deposition• Increase protein anabolism• Decrease blood cholesterol• Facilitate calcium uptake• Promotes hydration of skin• Feminizes brain

Menopause: cessation of ovarian and menstrual cycles. Usually occurs between ages 46 and 54. Due to ovaries decreased responsiveness

to gonadotropins.

Menopause affects: changes in sexual desire triggers mood swings causes debilitating hot flashes may lead to bone and heart problems short-term memory loss insomnia