The document summarizes the development of the female reproductive system. It begins with the formation of the genital ridge in the intermediate mesoderm at 3 weeks. At 5-6 weeks, primordial germ cells form the indifferent gonad. In the absence of the Y chromosome, the gonad develops into an ovary with cortical cords and primordial follicles. The ovaries descend into the pelvis guided by the gubernaculum. Meanwhile, the paramesonephric ducts form the fallopian tubes, uterus and upper vagina. The vagina develops from the sinovaginal bulbs and vaginal plate. Remnants of the mesonephric ducts include the epoophoron and

1. Development of female
reproductive system
Dr Shaifaly Madan Rustagi

2. Learning objectives
• Layers of embryo
• Development of ovary
• Descent of ovaries
• Development of paramesonephric ducts
• Remnants of mesonephric ducts
• Development of vagina
• Defects in development of uterus and vagina

3. Intermediate
mesoderm
The three layers of embryo….

4. Mesonephros and gonad

5. Development of Ovary

6. At 3 weeks of development
On either side of mesentery the intermediate mesoderm shows a thickening the
genital ridge(which will form indifferent gonad) medial to the mesonephros

7. At 5-6 weeks
The primordial germ cells from yolk sac endoderm
travel via dorsal mesentery to get incorporated into
the differentiating gonad in the genital ridge.

8. Indifferent gonad
Gonads begin to develop during 5th week from genital ridge
Gonads are first undifferentiated and have only cortex and medulla.
The type of gonad to be developed is determined at fertilization.

9. Sequence of events
• Normal absence of the Y chromosome or the sex-
determining region of the Y chromosome (SRY gene)
• Somatic sex cords of the indifferent gonad do not
produce Testis determining factor (TDF )
• No differentiation of gonad into a testis and its
subsequent production of antimüllerian hormone and
testosterone
• The indifferent gonad becomes an Ovary and formation
of female duct system

10. • Gonadal development occurs slowly in
females
• The X chromosomes bear genes for ovarian
development
• Until 10th week: ovary cannot be identified
histologically

11. Primitive sex cords cords do not become prominent.
They migrate and extend into the medulla and form rete ovarii,
which is rudimentary and disappears
Primitive sex cords

12. Surface
epithelium gives
rise to a second
generation of
cortical cords into
which primordial
germ cells are
incorporated.

13. These cords split into isolated cell clusters called
primordial follicles -each of which consists of an
oogonium derived from a primordium germ cell
surrounded by a single layer of flattened follicular cells
derived from surface epithelium.

14. • Primordial follicles will form primary oocytes
• Number of primary oocytes at 20 weeks of
IUL – 7 million
• Number of primary oocytes at puberty –
4,00,000

15. The ovary separates from regressing mesonephros
and suspended by a mesentery ,the mesovarium

16. Descent of ovaries

17. Gonad and Gubernaculum
The ovaries descend from posterior abdominal wall to reach the pelvic
cavity.
The gubernaculum (a mesodermal condensation ) attaches cranially to the
caudal pole of the ovary and caudally to internal surface of labial swellings
K :Kidney , Cm: Cranial mesentery, d duct CSL cranial suspensory ligament ,bl : bladder

18. The cranial part of gubernaculum becomes ovarian ligament (between
lower pole of ovary and side of uterus )
The caudal part of gubernaculum becomes round ligament of uterus
(from the side of the uterus to the labia majora )

19. Development of
paramesonephric ducts

20. Genital ducts
• Two pairs of genital ducts
are initially present in both
sexes:
(1) the mesonephric (wolffian)
ducts, which give rise to the
male ducts and a derivative,
the seminal vesicles; and
(2) the paramesonephric
(müllerian) ducts, which
form the oviducts or
fallopian tubes , uterus-
fundus,body and cervix and
vaginal fornices .

21. Genital ducts in cross section
At this time the intermediate mesoderm has mesonephric tubules
draining into mesonephric duct or wolffian duct adjacent to genital
ridge and mullerian duct or paramesonephric duct beginning to show

22. Paramesonephric duct in horizontal and
longitudinal section
• Formation of each paramesonephric (PMN) duct begins early in the sixth
week as an invagination of coelomic epithelium in the lateral wall of the
cranial end of the urogenital ridge and adjacent to each mesonephric duct
(In picture in red)

23. Parts of paramesonephric (PMN) ducts
• Initially 3 parts are
recognizable
1. Cranial vertical part :
which opens within the
coelomic cavity
2. Mid horizontal part :which
crosses the mesonephric
duct
3. Caudal vertical part :
which fuses in the midline
with its partner from
opposite side
(Please refer the blue ducts in
the picture)

24. Derivatives of Paramesonephric ducts
• With descent of ovaries into the pelvic inlet ,the first two parts i.e cranial
vertical and mid horizontal parts will develop into fallopian tube /oviducts
• The cranial end of the PMN duct remains open and will form the ostium of
the oviduct.
• The third part i.e.caudal vertical parts will fuse in midline to form a
uterovaginal primordium.(UVP)

25. Development of PMN ducts (contd)
• In the midline UVP initially has a uterine septum where the two PMN
ducts fused but later fuse to form uterine canal.
• Contact of the UVP with the urogenital sinus forms the sinus tubercle
on the posterior wall of urogenital sinus

26. Derivatives of Uterovaginal primordium(UVP)
• The UVP gives rise to the fundus, body, and isthmus of the
uterus, specifically the endometrial epithelium and glands of
the uterus.
• The UVP forms cranial part of vagina.(fornices part)
• The endometrial stroma and smooth muscle of the
myometrium are derived from adjacent splanchnic
mesenchyme.
• The epithelium of the cervix forms from the lower aspect of
UVP.

27. Remnants of mesonephric duct
• The mesonephric tubules and ducts regress in the female.
• Cranial part of duct forms epoophoron
• Mesonephric tubules form paroophoron
• At the caudal end a remnant the gartners duct /gartners cyst remains.

28. Development of vagina

29. Formation of sinovaginal bulbs
• The solid tip of the
fused
paramesonephric
ducts ,the sinus
tubercle reaches the
dilated pelvic part of
urogenital sinus (UGS)
• The sinus tubercle
induces the formation
of paired endodermal
outgrowths in the UGS
called sinovaginal
bulbs
• The sinovaginal bulbs
fuse to form a vaginal
plate.

31. • The epithelium of the vagina is
derived from the peripheral
cells of the vaginal plate.
• The vaginal plate (arising from
UGS) keeps on proliferating
thus increasing the distance
between the uterus and the
UGS
• Four wing like expansions of
the fused PMN ducts will
encircle the cranial parts of
the vaginal plate and become
the vaginal fornices.

32. • The central cells of the vaginal
plate break down (by the
process of apoptosis) and a
canal is formed which is
continuous cranially with the
uterine canal.
• Caudally it is separated from
the cavity of the UGS by a
transverse membrane, the
hymen.
• At birth, this hymen usually
ruptures in the middle and
remains as a thin fold of
mucous membrane within the
vaginal orifice

33. Formation of broad ligament

34. • Fusion of the PMN ducts
also brings together a fold of
peritoneum that becomes
the broad ligament
• The formation of broad
ligament divides the pelvic
cavity into two peritoneal
cavities –rectouterine pouch
and the vesicouterine
pouch.
• Along the sides of uterus –
between the layers of broad
ligament , mesenchyme
proliferates and
differentiates into loose
connective tissue and
smooth muscle-the
parametrium.

35. Auxillary genital glands in females
• Buds grow from the urethra into surrounding
mesenchyme and form bilateral mucus
secreting glands and paraurethral glands
(corresponding to prostate in male )
• Outgrowths from urogenital sinus form the
greater vestibular glands in lower third of
labia majora (homologous to bulbourethral
glands in male)

36. Uterine and vaginal defects in
development

37. • Uterine didelphys results from failure of fusion of the
inferior parts of paramesonephric ducts .
• The uterus is entirely double and each one enters a
separate vagina.

38. • Uterus bicornis is one of
the common anomalies in
which the malfusion
involves only the superior
part of PMN ducts resulting
in a double horned uterus
entering a single vagina.
• Uterus bicornis unicollis
with one rudimentary horn-
One of the PMN ducts may
get partially or completely
atretic ,a part of the duct
may develop

39. • Uterus arcuatus : least severe form, uterus only slightly indented in
the middle
• Unicornuate uterus: develops when one paramesonephric duct fails
to develop,this results in a uterus with one uterine tube.
• Septate uterus : Uterine septum does not regress completely
/partially

40. Absence of vagina: Due to failure of sinovaginal bulbs
to develop and form the vaginal plate.
• Occurrence 1in 5000 newborns
Vaginal Atresia:
Failure of canalization of vaginal plate results in atresi a
(blockage) of the vagina.
Imperforate hymen: Failure of inferior end of vaginal
plate to perforate results in imperforate hymen.

41. https://youtu.be/MureNA-RSZM

42. Thankyou