Reproductive Systems
A) Sex Determination
- Determination of development of sexual characteristics
- Embryo exhibits gender bi-potential
o Mullerian ducts (female reproductive ducts)
o Wolffian ducts (male repro. Ducts)
- Around week 7 → SRY gene is activated – on Y chromosome & directs development of male gonads
- PRESENT SRY (XY) → causes gonads to descend & develop into testes
o Testes produce male sex hormones → testosterone (stimulates Wolffian duct development)
→ AMH (anti-mullerian hormone)
- ABSENT SRY (XX) → gonads develop into ovaries → produce female sex hormones
B) Female Reproductive System
a. Anatomy
i. Internal genitalia (primary repro. organs) – found in true pelvis
1. Vagina, uterus, cervix, fallopian tubes, ovaries
ii. External genitalia (secondary repro. organs) – found outside true pelvis
b. Oogenesis (gametogenesis)
i. Development of ova from oogonia (primordial germ cell)
ii. If fertilization does NOT occur ➔ Meiosis II is not complete
1. Oogonia (2n) divides by mitosis →
Primary oocytes (2n)
2. Primary oocytes enter Meiosis I just
BEFORE BIRTH and stalls at
Prophase 1
3. After PUBERTY, the rise in LH & FSH
levels cause the Primary oocyte to
complete Meiosis I → becomes
secondary oocyte (n) & polar body
4. Secondary oocyte enters Meiosis II
BUT STOPS at Metaphase 2 if NOT
fertilised
5. Once fertilised in fallopian tube →
completes Meiosis II → forms
fertilized, mature ovum & polar
body (disintegrates)
, c. Local Prostaglandins
i. PGF2 - stimulates uterine contractions & corpus luteum (CL) regression
ii. PGE2 - stim. uterine contraction
d. Hormones
i. Hypothalamus
1. GnRH (gonadotropin releasing hormone)
→ stim. release of LH & FSH from anterior pituitary gland
ii. Anterior pituitary gland
1. LH → promotes follicle maturation, ovulation, oestrogen secretion, CL formation
2. FSH → promotes follicular growth & development
3. Prolactin → stim. milk production
iii. Posterior Pituitary gland
1. Oxytocin
a. Promotes milk let-down reflex (ejection)
b. Promotes uterus contraction during parturition (giving birth)
c. Stim. peristalsis → transports sperm via fallopian tubes
iv. Ovaries
1. Oestrogen
a. Secreted from theca cells in follicles due to LH
b. Principal oestrogen = oestradiol
c. Causes growth of repro. organs
d. Promotes development of secondary sexual characteristics
2. Inhibin
a. Secreted by granulosa cells in follicles
b. Inhibits FSH
c. Peptide hormone
3. Progesterone
a. Produced in corpus luteum
b. Promotes thickening of endometrium
c. Inhibits uterus contractions → maintains pregnancy
d. Prepares mammary glands for lactation
v. Placenta
1. Human chorionic gonadotropin (hCG)
a. Species specific hormone
b. Maintains pregnancy by supporting CL (similar structure to LH)
c. Levels measured to detect pregnancy
2. Relaxin
a. Relaxes ligaments in pelvis
b. Softens & shortens cervix
3. Progesterone
A) Sex Determination
- Determination of development of sexual characteristics
- Embryo exhibits gender bi-potential
o Mullerian ducts (female reproductive ducts)
o Wolffian ducts (male repro. Ducts)
- Around week 7 → SRY gene is activated – on Y chromosome & directs development of male gonads
- PRESENT SRY (XY) → causes gonads to descend & develop into testes
o Testes produce male sex hormones → testosterone (stimulates Wolffian duct development)
→ AMH (anti-mullerian hormone)
- ABSENT SRY (XX) → gonads develop into ovaries → produce female sex hormones
B) Female Reproductive System
a. Anatomy
i. Internal genitalia (primary repro. organs) – found in true pelvis
1. Vagina, uterus, cervix, fallopian tubes, ovaries
ii. External genitalia (secondary repro. organs) – found outside true pelvis
b. Oogenesis (gametogenesis)
i. Development of ova from oogonia (primordial germ cell)
ii. If fertilization does NOT occur ➔ Meiosis II is not complete
1. Oogonia (2n) divides by mitosis →
Primary oocytes (2n)
2. Primary oocytes enter Meiosis I just
BEFORE BIRTH and stalls at
Prophase 1
3. After PUBERTY, the rise in LH & FSH
levels cause the Primary oocyte to
complete Meiosis I → becomes
secondary oocyte (n) & polar body
4. Secondary oocyte enters Meiosis II
BUT STOPS at Metaphase 2 if NOT
fertilised
5. Once fertilised in fallopian tube →
completes Meiosis II → forms
fertilized, mature ovum & polar
body (disintegrates)
, c. Local Prostaglandins
i. PGF2 - stimulates uterine contractions & corpus luteum (CL) regression
ii. PGE2 - stim. uterine contraction
d. Hormones
i. Hypothalamus
1. GnRH (gonadotropin releasing hormone)
→ stim. release of LH & FSH from anterior pituitary gland
ii. Anterior pituitary gland
1. LH → promotes follicle maturation, ovulation, oestrogen secretion, CL formation
2. FSH → promotes follicular growth & development
3. Prolactin → stim. milk production
iii. Posterior Pituitary gland
1. Oxytocin
a. Promotes milk let-down reflex (ejection)
b. Promotes uterus contraction during parturition (giving birth)
c. Stim. peristalsis → transports sperm via fallopian tubes
iv. Ovaries
1. Oestrogen
a. Secreted from theca cells in follicles due to LH
b. Principal oestrogen = oestradiol
c. Causes growth of repro. organs
d. Promotes development of secondary sexual characteristics
2. Inhibin
a. Secreted by granulosa cells in follicles
b. Inhibits FSH
c. Peptide hormone
3. Progesterone
a. Produced in corpus luteum
b. Promotes thickening of endometrium
c. Inhibits uterus contractions → maintains pregnancy
d. Prepares mammary glands for lactation
v. Placenta
1. Human chorionic gonadotropin (hCG)
a. Species specific hormone
b. Maintains pregnancy by supporting CL (similar structure to LH)
c. Levels measured to detect pregnancy
2. Relaxin
a. Relaxes ligaments in pelvis
b. Softens & shortens cervix
3. Progesterone
