REPRODUCTIVE SYSTEM
REPRODUCTIVE EMBRYOLOGY
Female Male
• Indifferent Gonads are derived from BOTH germ cells & primitive sex cords:
o Genital/Gonadal ridge [mesothelial layer of the peritoneum derived from germ
cells of endoderm in Week 4]
Indifferent o primitive sex cords [proliferation of epithelium of the genital ridges]
stage
*NB: Genital ridge (i.e. gonads) connected to scrotum/labia via gubernaculum ( a ligamentous
[Wk 6-7] structure derived from mesenchyme)
Embryology Internal Genitalia External Genitalia Internal Genitalia External Genitalia
• No Y chr. = No SRY gene Mesenchymal cells migrate to • SRY gene = triggers primitive SAME
cloacal membrane è forms cloacal sex cord development to form Ø Proliferation of ectoderm and
• No Leydig cells = No testosterone è
folds: testis cords surrounded by
primitive sex cords degenerate = NO mesoderm around closed
• Fusion of folds cranially = tunica albuginea membrane forms genital
testic cords formed
genital tubercle • Testis cords = 2 cell types = tubercle, genital swelling and
• No Sertoli cells = NO anti-mullerian congenital fold
• Fusion of folds caudally = Sertoli cells & Leydig cells
hormone ® paramesnopheric ducts
urethral folds (anterior) and
Un- • Gonadal epithelium proliferate è
anal folds (posterior)
differentiated becomes cortical cords ® surround
stage germ cells with epithelial follicular • Either side of folds = Genital
cells ® primordial follicle swellings
1. Sertoli cells (germ) ® epithelial Testes secrete androgen (DHT) to:
Anti-mullerian hormone cells ® Secrete anti-Mullerian
Oestrogen causes: hormone to degenerate • Elongate genital tubercle è
• paramesnopheric ducts = fallopian Paramesonephric ducts phallus
tubes & uterus, cervix and upper 1/3 of • Genital tubercle elongates
(becomes appendix testis) ®
vagina è clitoris
At puberty: cords acquire • Pull Urethral folds è
• Proximal part = separature tube • Urethral folds (labia minora) lumen ® become seminiferous urethral groove è fold over
& genital swellings (labia è penile urethra [4TH
• Distal part – uterus fusion 2. Leydig cells ® mesoderm cells MONTH]
majora) do NOT fuse
® produce TT to induce
• Urogenital groove remains mesonephric ducts • Genital swellings è scrotal
NB: urogenital sinus è sinovaginal bulbs è open è vestibule differentiation è epididymis, swellings, moving caudally
lower 2/3 vagina vas deferens and seminal to eventually form the
vesicles scrotum
Differentiated
stage
Proximal mesonephric duct = highly convoluted epididymis
Urogenital sinus = prostrate gland + bulbourethral glands
• Ovaries migrate caudally but to lesser extent than testes è reaches just within • Testes migrate caudally as foetus grows
the true pelvis
• 28th week: Testes enter inguinal canal è reach scrotum by 33rd week
• Remnant of gubernaculum = ovarian ligament + round ligament of the uterus [retains testicular arterial supply from lumbar aorta]
• Remnant of gubernaculum = Scrotal ligament
ANOMALIES
• Hypospadius = external urethral orifice on ventral surface of
penis/glans
• Cryptorchidism = failure of testes to descend into scrotum leading to
ectopic testes [due to unusual descent route]
Descent of
gonads • Ectopic testes – undescended testes away from normal descent
pattern
, NORMAL MENSTRUAL CYCLE (21-35 days)
MENSES PHASE
Follicular phase varies Luteal phase is FIXED = 14 days Loss of star-
shaped glands
Stromal (slough +
haemorrhage)
PROLIF PHASE
Test tube glands
Anti-Mullerian hormone = indicates SIZE of
Mitotic figures
primordial follicle pool = GF secreted by
primordial follicles
SECRET PHASE
Star shaped
corkscrew gland
dilated
Coiled arteries
Estrogen influenced Progesterone influenced (thecal)
TOP medications)
• PGF2a = PGE2 • PGF2a > PGE2 (2x) = vasoconstrict • Misoprostol – synthetic PG – induce
• Thromboxane – vasoconstrict uterine contractions
• Fibrinolytic activity (↓clot) • Mifepristone = synthetic anti-PG -
↓embyro implantation
• Prostacyclin (PGI2) = arachidonic acid
metabolite = relax uterine muscle tone
Stages Day / Length Hormones Event
0-13 (Variable) • 1st day of cycle = 1st day of period
(Older = shorter - fewer • Folliculogenesis = primordial follicles develop into a single mature, dominant Graafian follicle
Phase 1: follicular eggs, ↑FSH
[*limited # of follicles at birth]
(proliferative) PCOS = longer as no
Primordial ® primary ® secondary ® tertiary “antral” follicles ® Graafian follicles
dominant follicle to
suppress others) ↑Estrogen • Estrogen causes endometrial proliferation = thicker endometrium
HPA +ve feedback • ↑ 17β-oestradiol ↑↑ FSH & ↑↑ LH è ovulation
Phase 2: • Breakdown wall of graafian follicle ® ruptures ® releases secondary oocyte into peritoneal
14
mid-cycle or cavity
[LH surge day 9-16] ↑↑ FSH & LH
ovulation
• Picked up by fimbriae of Fallopian tube ® infundibulum ® ampulla via ciliary movement of tubal
epithelium on fallopian tube
1) ↑↑ LH → (+) theca cells → ↑ progesterone (major) drive development of corpus luteum
Day 15-28 2) Corpus luteum (ruptured Graafian follicle (i.e. granulosa and theca cells) è also
Phase 3:
Fixed at 14 days ↑ LH = synthesizes/secretes17β-oestradiol
luteal (secretory)
[ovulation to start of ↑ progesterone
phase • makes endometrium more glandular support embryo implantation
menstruation]
• increases hypothalamic-set point to raise basal body temperature
• Corpus luteum regresses ® replaced by fibrotic scar (corpus albicans)
o Spiral arteries contract to reduce blood loss during menstruation
Menses
o regression = abrupt loss of progesterone and 17β- oestradiol
• No fertilisation = endometrial lining sloughs è menstrual bleeding
Phase 4: menses of ovulation day + 14 days • Fertilisation è syncytiotrophoblasts secrete hCG è preserves corpus luteum
pregnancy = menstruation o Synctiotrophoblasts produce villi to increase surface area around maternal
uterine blood vessels
Pregnancy o Thin membrane of cytotrophoblasts allows diffusion and removal of nutrients,
wastes, gas ® gradually develops into placenta
• corpus luteum continues to produce/secrete progesterone and 17β-eostradiol
• After 8 weeks: Placenta takes over to produce PG, E2
Hormone Oestrogen Progesterone
Cells Granulosa cells Theca cells
Origin Ovaries Corpus luteum (Ovary) /
Placenta (5-10/40)
Role Develop Female 2o sex Maintain pregnancy
characteristics (breast, Ø Drive corpus luteum
vulva, vagina) development
Fallopian • Proliferation • Reduce # of cilia
tube • Secretion of sugar • Reduce secretions
rich fluid
Endometrial • Angiogenesis in Thicken and maintain
effect uterus endometrium
• Endometrial
proliferation
Cervix Thins cervical mucus Thicken cervical mucus Hormonal Changes During Puberty (TANNER STAGING)
1) GH increases initially è GROWTH spurt
Other Stop milk production • Stop milk production
• ↑ basal body temp 2) HT secretes GnRH during sleep then during day ® rising FSH/LH ® rising
(peripheral vasodilation + estrogen and progresterone levels
increased metabolism) 3) FSH levels plateau (year before menarche)
• ↑ tidal volume (relax
diaphragm and intercostals) 4) LH continue to rise and spike just before they induce menarche
REPRODUCTIVE EMBRYOLOGY
Female Male
• Indifferent Gonads are derived from BOTH germ cells & primitive sex cords:
o Genital/Gonadal ridge [mesothelial layer of the peritoneum derived from germ
cells of endoderm in Week 4]
Indifferent o primitive sex cords [proliferation of epithelium of the genital ridges]
stage
*NB: Genital ridge (i.e. gonads) connected to scrotum/labia via gubernaculum ( a ligamentous
[Wk 6-7] structure derived from mesenchyme)
Embryology Internal Genitalia External Genitalia Internal Genitalia External Genitalia
• No Y chr. = No SRY gene Mesenchymal cells migrate to • SRY gene = triggers primitive SAME
cloacal membrane è forms cloacal sex cord development to form Ø Proliferation of ectoderm and
• No Leydig cells = No testosterone è
folds: testis cords surrounded by
primitive sex cords degenerate = NO mesoderm around closed
• Fusion of folds cranially = tunica albuginea membrane forms genital
testic cords formed
genital tubercle • Testis cords = 2 cell types = tubercle, genital swelling and
• No Sertoli cells = NO anti-mullerian congenital fold
• Fusion of folds caudally = Sertoli cells & Leydig cells
hormone ® paramesnopheric ducts
urethral folds (anterior) and
Un- • Gonadal epithelium proliferate è
anal folds (posterior)
differentiated becomes cortical cords ® surround
stage germ cells with epithelial follicular • Either side of folds = Genital
cells ® primordial follicle swellings
1. Sertoli cells (germ) ® epithelial Testes secrete androgen (DHT) to:
Anti-mullerian hormone cells ® Secrete anti-Mullerian
Oestrogen causes: hormone to degenerate • Elongate genital tubercle è
• paramesnopheric ducts = fallopian Paramesonephric ducts phallus
tubes & uterus, cervix and upper 1/3 of • Genital tubercle elongates
(becomes appendix testis) ®
vagina è clitoris
At puberty: cords acquire • Pull Urethral folds è
• Proximal part = separature tube • Urethral folds (labia minora) lumen ® become seminiferous urethral groove è fold over
& genital swellings (labia è penile urethra [4TH
• Distal part – uterus fusion 2. Leydig cells ® mesoderm cells MONTH]
majora) do NOT fuse
® produce TT to induce
• Urogenital groove remains mesonephric ducts • Genital swellings è scrotal
NB: urogenital sinus è sinovaginal bulbs è open è vestibule differentiation è epididymis, swellings, moving caudally
lower 2/3 vagina vas deferens and seminal to eventually form the
vesicles scrotum
Differentiated
stage
Proximal mesonephric duct = highly convoluted epididymis
Urogenital sinus = prostrate gland + bulbourethral glands
• Ovaries migrate caudally but to lesser extent than testes è reaches just within • Testes migrate caudally as foetus grows
the true pelvis
• 28th week: Testes enter inguinal canal è reach scrotum by 33rd week
• Remnant of gubernaculum = ovarian ligament + round ligament of the uterus [retains testicular arterial supply from lumbar aorta]
• Remnant of gubernaculum = Scrotal ligament
ANOMALIES
• Hypospadius = external urethral orifice on ventral surface of
penis/glans
• Cryptorchidism = failure of testes to descend into scrotum leading to
ectopic testes [due to unusual descent route]
Descent of
gonads • Ectopic testes – undescended testes away from normal descent
pattern
, NORMAL MENSTRUAL CYCLE (21-35 days)
MENSES PHASE
Follicular phase varies Luteal phase is FIXED = 14 days Loss of star-
shaped glands
Stromal (slough +
haemorrhage)
PROLIF PHASE
Test tube glands
Anti-Mullerian hormone = indicates SIZE of
Mitotic figures
primordial follicle pool = GF secreted by
primordial follicles
SECRET PHASE
Star shaped
corkscrew gland
dilated
Coiled arteries
Estrogen influenced Progesterone influenced (thecal)
TOP medications)
• PGF2a = PGE2 • PGF2a > PGE2 (2x) = vasoconstrict • Misoprostol – synthetic PG – induce
• Thromboxane – vasoconstrict uterine contractions
• Fibrinolytic activity (↓clot) • Mifepristone = synthetic anti-PG -
↓embyro implantation
• Prostacyclin (PGI2) = arachidonic acid
metabolite = relax uterine muscle tone
Stages Day / Length Hormones Event
0-13 (Variable) • 1st day of cycle = 1st day of period
(Older = shorter - fewer • Folliculogenesis = primordial follicles develop into a single mature, dominant Graafian follicle
Phase 1: follicular eggs, ↑FSH
[*limited # of follicles at birth]
(proliferative) PCOS = longer as no
Primordial ® primary ® secondary ® tertiary “antral” follicles ® Graafian follicles
dominant follicle to
suppress others) ↑Estrogen • Estrogen causes endometrial proliferation = thicker endometrium
HPA +ve feedback • ↑ 17β-oestradiol ↑↑ FSH & ↑↑ LH è ovulation
Phase 2: • Breakdown wall of graafian follicle ® ruptures ® releases secondary oocyte into peritoneal
14
mid-cycle or cavity
[LH surge day 9-16] ↑↑ FSH & LH
ovulation
• Picked up by fimbriae of Fallopian tube ® infundibulum ® ampulla via ciliary movement of tubal
epithelium on fallopian tube
1) ↑↑ LH → (+) theca cells → ↑ progesterone (major) drive development of corpus luteum
Day 15-28 2) Corpus luteum (ruptured Graafian follicle (i.e. granulosa and theca cells) è also
Phase 3:
Fixed at 14 days ↑ LH = synthesizes/secretes17β-oestradiol
luteal (secretory)
[ovulation to start of ↑ progesterone
phase • makes endometrium more glandular support embryo implantation
menstruation]
• increases hypothalamic-set point to raise basal body temperature
• Corpus luteum regresses ® replaced by fibrotic scar (corpus albicans)
o Spiral arteries contract to reduce blood loss during menstruation
Menses
o regression = abrupt loss of progesterone and 17β- oestradiol
• No fertilisation = endometrial lining sloughs è menstrual bleeding
Phase 4: menses of ovulation day + 14 days • Fertilisation è syncytiotrophoblasts secrete hCG è preserves corpus luteum
pregnancy = menstruation o Synctiotrophoblasts produce villi to increase surface area around maternal
uterine blood vessels
Pregnancy o Thin membrane of cytotrophoblasts allows diffusion and removal of nutrients,
wastes, gas ® gradually develops into placenta
• corpus luteum continues to produce/secrete progesterone and 17β-eostradiol
• After 8 weeks: Placenta takes over to produce PG, E2
Hormone Oestrogen Progesterone
Cells Granulosa cells Theca cells
Origin Ovaries Corpus luteum (Ovary) /
Placenta (5-10/40)
Role Develop Female 2o sex Maintain pregnancy
characteristics (breast, Ø Drive corpus luteum
vulva, vagina) development
Fallopian • Proliferation • Reduce # of cilia
tube • Secretion of sugar • Reduce secretions
rich fluid
Endometrial • Angiogenesis in Thicken and maintain
effect uterus endometrium
• Endometrial
proliferation
Cervix Thins cervical mucus Thicken cervical mucus Hormonal Changes During Puberty (TANNER STAGING)
1) GH increases initially è GROWTH spurt
Other Stop milk production • Stop milk production
• ↑ basal body temp 2) HT secretes GnRH during sleep then during day ® rising FSH/LH ® rising
(peripheral vasodilation + estrogen and progresterone levels
increased metabolism) 3) FSH levels plateau (year before menarche)
• ↑ tidal volume (relax
diaphragm and intercostals) 4) LH continue to rise and spike just before they induce menarche
