7. PARAMESONEPHRIC DUCT
• Mullerian ducts form 5-6th week.
• Formed by invagination of coelomic epithelium.
• Wolffian ducts serve as migration template.
• If wolffian duct fails mullerian duct donot develop.
• Fuse with other side caudally in midline to form UTERO-
VAGINAL CANAL & sheet of peritoneum which forms BROAD
LIGAMENT
• Caudal end joins phallic part of UGS
• In females it forms tubes, uterus & upper 1/3rd of vagina
• In males remnants forms prostratic utricle (~uterus) & appendix
of testis
8.
9. 3 phases of Mullerian duct development
PHASES GENE
Selection of cells in coelomic
epithelium
Lim 1
Epithelial invagination Wnt family
Duct elongation
Duct differentiation
Pax2
Pax8
10.
11. MALE EMBRYONIC
STRUCTURE
FEMALE
Testis INDIFFERENT GONAD Ovary
Seminiferous tubules CORTEX Follicles
Rete testis MEDULLA Rete ovary
Gubernaculum testis GUBERNACULUM Ovarian & Round lig
Efferent ductules MESONEPHRIC TUBULES Epo & paraoophoron
Duct & appendix of Epididymis
Ductus deferens
Ejaculatory duct & Seminal vesicle
Ureter, renal pelvis, Collecting duct
MESONEPHRIC DUCT Duct of epoophoron
Duct of Gartner
No homologous
Same
Appendix of testis PARAMESONEPHRIC DUCT Uterus, Tubes, upper
1/3rd of vagina & Hydatid
Bladder
Urethra
Prostate
Prostatic utricle
UROGENITAL SINUS Bladder
Urethra
Urethral & paraurethral
glands
Vagina
14. UTERUS & TUBES
Begins @ 7-8wk completes by 12th wk
EPITHELIUM: fused paramesonephric duct
MYOMETRIUM: surrounding mesoderm increase in thickness
& unfused parts embedded to form fundus
TUBES: develop from unfused paramesonephric ducts
FIMBRIAE: invagination of coelomic epithelium
15.
16.
17. CERVIX & VAGINA
@ 20th week condensation of stromal cells around fused
mullerian duct forms cervix
Part where Uterovaginal canal (meso) & Phallic part of UGS
(endo) meet lead to formation of vaginal plate.
Sinovaginal bulb form from endoderm
Vaginal plate from mesoderm & endoderm
Canalisation of vaginal plate
Hymen(endo) is junction of vagina plate & UGS
18.
19. EXTERNAL GENITALIA
Elongation of UG membrane occurs
Mesoderm on both sides heap up to form primitive URETHRAL
FOLDS later forms Labia Minora (endo & ecto)
3 elevations (9 weeks):
1. GENITAL TUBERCLE forms clitoris
2. GENITAL SWELLINGS forms Labia Majora
UG membrane breaks leads to formation of VESTIBULE
22. OVARY
Genital ridges develop on medial side of mesonephros by
thickening of coelomic epithelium
Cords of cells(sex cords or medullary cords) grows into
underlying mesoderm
Primordial germ cells migrate to form oocytes
Sex cord breaks forms masses that surround one oocyte to
form PRIMORDIAL FOLLICLE
INTERSTITIAL GLANDS differentiate from mesenchyme of
gonad
26. BIPOTENTIAL GONAD
TESTIS OVARY
• TDF on SRY gene on Y
• AMH
• SOX9
• FGF9
CORTICAL REGRESSION
MEDULLARY PROLIFERATION
• Lack of SRY
• DAX1
• WNT4
• RSPO1
CORTICAL PROLIFERATION
MEDULLARY REGRESSION
LEYDIG CELLS SERTOLI CELL
TESTOSTERONE
WOLFFIAN
DUCT
DHT
MALE EXTERNAL GENITALIA
AMH
MULLERIAN
DUCT
FEMAL EXTERNAL
GENITALIA
2 wk later
27. 2.Differentiation
Male phenotype depend on AMH & testosterone
Female phenotype depend on absence of these products
AMH Receptor gene mutation in 46XY –
Internal female genitalia
External male genitalia
Small amount of AMH in ovary help in oocyte maturation &
follicular development
Serum AMH levels correlate with follicles present & response to
ovulation induction
31. • Ovary forms in lumbar region descends to true pelvis.
• Gubernaculum extend from ovary to labium majus .
• Attach at junction of tube & uterus.
• Persists as Round ligament
DESCENT OF OVARY
32. Intermediate mesoderm: 3rd week
Pronephros: 4th week & regress
Mesonephros: 4th week function @ 6-10th week
Metanephros: 4th week function from 12th week
Mullerian ducts: 6th week
Primordial germ cells develop in yolk sac : 4th
Migrate : 6th
Gonads remain as indifferent : 6th
Interstitial cells produce testosterone : 8th
Sec sex cords: 10-12th
Primordial follicles: 16th
Urethral folds: 3rd mth
External genitalia: 7th and 9th week
Urorectal septum: 4th and 7th week
Vagina: 20th
TIME TABLE OF EVENTS