Male reproduction

what are the main functions of the male reproductive system

• produce sperm (spermatogenesis)

• deliver sperm

• produce androgens (testosterone)

where are the testes located

In scrotum outside the abdominal cavity

What is the path sperm takes from testes to outside

vas efferentia → epididymis → ductus deferens → ejaculatory duct → urethra

why are testes outside the body

require temperature 2–4°C below body temperature for spermatogenesis

what structure helps testes descend

gubernaculum

what is cryptorchidism

failure of testes to descend into scrotum

effects of cryptorchidism on fertility

• testosterone normal

• spermatogenesis impaired → infertility

Where does spermatogenesis occur

seminiferous tubules

where are mature sperm found in tubules

in the lumen (center)

What are the three main part of sperm

• head (nucleus + acrosome)

• Midpiece (mitochondria)

• tail (motility)

what are the three main stages

1. mitosis (spermatogonia → primary spermatocytes)

2. Meiosis (→ haploid spermatids)

3. Spermiogenesis (maturation to spermatozoa)

How many spermatids come from one primary spermatocyte

four haploid spermatids

what do Sertoli cells do

• support and nourish sperm

• form blood-testis barrier

• remove defective cells

• secrete fluid and androgen-binding protein

What do leydig cells produce

Testosterone

What stimulates testosterone production

LH (acts on Leydig cells)

What stimulates spermatogenesis

FSH (acts on Sertoli cells)

What hormone controls LH and FSH release

GnRH from hypothalamus

How does testosterone regulate the system

Inhibits GnRH and LH (negative feedback)

What inhibits FSH

Inhibin from Sertoli Cells

What happens to sperm in epididymis

• gain motility

• gain fertilization ability

• fluid reabsorption

what do seminal vesicles produce

• fructose (energy)

• prostaglandins

• majority of semen volume

what does prostate gland do

• alkaline fluid (neutralizes acidity)

• Clotting enzymes & PSA

What do bulbourethral glands do

• lubrication

• Neutralize urethra

what does testosterone do before birth

masculinizes reproductive tract and genitalia

What does testosterone do before birth

Masculinizes reproductive tract and genitalia

what does testosterone do at puberty

• spermatogenesis

• growth of reproductive organs

• libido

secondary effects of testosterone

• muscles growth

• deep voice

• hair growth

• aggression

what is puberty

gonads reach full reproductive and hormonal function

what triggers puberty

Increased GnRH secretion → LH & FSH increase

What axis is activated at puberty

Hypothalamic-pituitary gonadal (HPG) axis

Do males immediately have full fertility at puberty

No - reduced sperm production and fertility initially

order of hormone release in males

GnRH → LH → Testosterone