male reproductive

4 major functions of male/female system

1. Form gametes

2. intercourse

3. fertilization

4. Gestation (supporting development of the fetus)

Leutinizing hormone

stimulates testes to produce testosterone (T) by binding to
interstitial endocrine cells and stimulating them to secrete T

FSH

stimulates spermatogenesis by stimulating sustentocytes to
release androgen-binding protein (ABP) : keeps T high

scrotum

Sac of skin and superficial fascia that hangs outside abdominopelvic cavity

3 degrees C lower

Dartos muscle

smooth muscle in superficial fascia that wrinkles skin

cremaster muscle

skeletal muscle that elevates testes

testes

divided into lobules w/ seminif. tub

surrounded by tunica vaginalis (double layer)

Spermatic cord – holds nerves, blood vessels, lymphatics

Accessory sex glands

seminal glands

prostate gland

bulbo-urethral glands

Epididymis

Where sperm mature, gain ability to swim

contracts during ejaculation and expels sperm to ductus deferens

Ductus/ Vas deferens

Joins with seminal vesicle duct to form the ejaculatory duct

3 urethras

Prostatic urethra

Membranous urethra

Spongy urethra- thru P

Prepuce

foreskin of P

Corpus spongiosum

surrounds urethra and expands forming glans and bulb

Corpora cavernosa

paired dorsal erectile bodies

-erectile tissue fills with blood

Crura

proximal ends of corpora cavernosa that anchors penis to pubic arch

Perineum

Diamond-shaped region between pubic symphysis, coccyx and ischial tuberosities

Suspends scrotum and contains root or penis and anus

Seminal vesicle

Secrete alkaline, viscous fluid w/ fructose, prostaglandins and clotting proteins

Prostate gland

Secretes milky, slightly acidic fluid w/ citric acid, proteolytic enzymes

Bulbourethral (Cowper’s Glands)

Secrete alkaline fluid during sexual arousal that neutralizes urine acids, mucus for lubrication

cells of Seminiferous Tubules

Sustentocytes- supporting cells & play role in sperm formation

Spermatogenic cells- give rise to sperm

Myoid cells- contract to squeeze sperm
Interstitial endocrine cells: (Leydig cells)- produce androgens lil estrogen

steps of spermatogenesis

1. Mitosis of spermatogonia- (stem cell) forms two spermatocytes

2.Meiosis

3.Spermiogenesis- Spermatids become sperm

1. Mitosis of spermatogonia: forming spermatocytes

Begins with spermatogonia - stem cells

-Type A daughter cells remain at basal lamina to maintain pool of dividing germ cells
• Type B daughter cells move toward lumen and develop into primary spermatocytes.

2. Meiosis: spermatocytes to spermatids

Meiosis I:
• Primary spermatocyte (2n) form two secondary spermatocytes (n)

Meiosis II
• Secondary spermatocyte (n) rapidly undergoes meiosis II to become two spermatids (n)
• Nearly all genes are turned off and DNA compacted into dense pellets

3. Spermiogenesis: spermatids to sperm

spermatids develop :

head- nucleus + acrosome-enable sperm to penetrate egg

midpiece- mitochondria that produce ATP to move tail

tail- has flagellum

time for Spermatogenesis

64–72 days

Role of sustentocytes/ Sertoli cells

contain tight junctions that divide tubule into two compartments

• Basal compartment: spermatogonia and primary spermatocytes located here

• Adluminal compartment: meiotically active cells and tubule lumen are located

Secrete testicular fluid

2 mediators to regulate spermatogenesis

Androgen-binding protein (ABP): keeps testosterone levels high to stimulate spermatogenesis

Inhibin: inhibits spermatogenesis by inhibiting FSH release by anterior pituitary

blood testis barrier

formed by tight junctions

Prevents sperm antigens from escaping into blood

absent during immune system development, gained hit puberty

why sperm needs to be kept separated from rest of body

sperm isnt recognized as “self” bc sperm isn’t present untul puberty

immune system will attack its antigens if enter blood (separated by bood testis barrier)