Chapter 34 – Reproductive System

Wolffian

male

Müllerian

female

What determines sex?

• SRY gene present → male

• No SRY → female

Müllerian-inhibiting substance (MIS)

destroys female ducts

Male Development

Testosterone → develops Wolffian ducts

• Epididymis

• Vas deferens

• Seminal vesicles

Female Development

• No SRY → Müllerian ducts develop into:

  • Uterus

  • Fallopian tubes

  • Upper vagina

puberty

When it starts:

• Girls: 8–9 years

• Boys: ~11 years

Controlled by:

• Hypothalamus → Pituitary → Gonads (HPG axis)

Thelarche

breast development

Gonadarche

gonads mature

Adrenarche

↑ androgens

Menarche

first period

Fallopian tubes

fertilization happens here

Ovaries

produce eggs + hormones

Bartholin glands

lubrication

Skene glands

similar to prostate

Ovaries

Functions:

• Produce:

  • Ova (eggs)

  • Hormones:

    • Estrogen

    • Progesterone

Follicle development (oogenesis)

Process:

1. Primary oocyte (diploid)

2. → Secondary oocyte (haploid)

3. Ovulation occurs

4. If fertilized → becomes zygote

After Ovulation

• Empty follicle → corpus luteum

If fertilized:

• Corpus luteum stays → supports pregnancy

If NOT fertilized:

• Degenerates → menstruation starts

Estrogen

• Female development

• Menstrual cycle

Progesterone

Prepares uterus for pregnancy

Androgens

Libido, bone health

Menstrual cycle

⏱ Length:

• ~24–36 days

🔹 Phases:

1. Menstrual phase → bleeding

2. Follicular (proliferative) → lining builds

3. Ovulation → egg released

4. Luteal (secretory) → uterus prepares for pregnancy

🔹 Key Idea:

• If no fertilization → hormones drop → menstruation

Prolactin

makes milk

Oxytocin

releases milk

Seminal vesicles

fructose (energy for sperm)

Prostate

fluid + enzymes

Bulbourethral glands

lubrication

Sperm pathway

👉 Testes → Epididymis → Vas deferens → Ejaculatory duct → Urethra

Sperm structure

• Head → DNA + acrosome (enzymes)

• Midpiece → mitochondria (energy)

• Tail → movement

Spermatogenesis

• Sperm production in testes

Stimulated by:

• FSH → sperm production

• LH → testosterone production

Testosterone

Produced by Leydig cells

Functions:

• Male development

• Libido

• Muscle & bone growth

Aging changes

Female:

• ↓ Estrogen

• Menopause (no period for 12 months)

• ↑ FSH & LH

Male:

• Gradual ↓ testosterone

• ↓ libido

• Enlarged prostate (BPH)