Sexual differentiation in men and women with special attention to: Gonads, Mullerian structures, Wolffian ducts and urogenital sinus. Examples of gonadal dysgenesis Disorders of Sexual differentiation phenotype, chromosomal background, biological background, mechanism of hormonal disruption and endocrinological mechanisms leading to: Swyer syndrome, Androgen insensitivity syndrome and masculinization of female fetus in congenital adrenal hyperplasia. Describe three uterine anomalies resulting from variation in the fusion of Muller’s tubercles. Describe the anatomical situation in a patient with Mayer-Rokitanski-Kuster More presentations on https://www.drbbgosai.com/

2. Sexual Differentiation and
Embryology of male and
female genitals
Dr.B.B.Gosai

3. What we will learn?
 Sexual differentiation in men and women with special
attention to: Gonads, Mullerian structures, Wolffian ducts
and urogenital sinus.
 Examples of gonadal dysgenesis
 Disorders of Sexual differentiation phenotype,
chromosomal background, biological background,
mechanism of hormonal disruption and endocrinological
mechanisms leading to: Swyer syndrome, Androgen
insensitivity syndrome and masculinization of female fetus
in congenital adrenal hyperplasia. Describe three uterine
anomalies resulting from variation in the fusion of Muller’s
tubercles.
 Describe the anatomical situation in a patient with Mayer-
Rokitanski-Kuster

4. References:
 Langman’s Medical Embryology by
T.W.Sadler
 Keith Moore’s Developing Human
 www.med.unc.edu/embryo_images

5. Normal Sexual Differentiation
According to Jost paradigm 3 steps:
1. Establishment of chromosomal sex at
fertilization
2. Development of the undifferentiated
gonads into testes or ovaries
3. Differentiation of the internal ducts
and external genitalia

6. Sex determination begins at
fertilization: Chromosomal
Differentiation
Humans have 46 chromosomes
-22 pairs of autosomes
- 2 sex chromosomes
In general: females are - 46, XX
males are - 46, XY

7. Chromosomal Sex
 Testis Determining Factor
(TDF) on short arm of the
Y chromosome, adjacent
to the pseudoautosomal
boundary
 SRY (Sex Determining
Region on Y) gene is at
smallest region of the Y
chromosome capable of
inducing testicular
differentiation in humans
 ZFY (zinc finger gene on Y
chromosome)
 H-Y gene: A number of
women with 45,X gonadal
dysgenesis were found to be
H-Y antigen positive

8. SRY acts on the indifferent gonad to
start the process of male sexual
development

9. Stages of development of gonads:
1- Indifferent gonads: Before the 7th week as we can’t
differentiate between ovary and testis.
2- Differentiation: After the 7th week as gonads becomes
differentiated into testis or ovary under the SRY(Sex-
determining Region on Y chromosome) gene.
Sources of gonad development:
1- Intermediate mesoderm: forms the genital ridge.
2- Coelomic epithelium: forms sex cords.
3- Primitive (primordial) germ cells: form sperms or ova.
These germ cells are formed at 21th day in caudal part of the
wall of yolk sac (Hindgut). Germ cells migrate through dorsal
mesentery to the gonad (at 6th w.)

10. Migration of primordial germ cells from the posterior extra-embryonic mesoderm
through the mesenteries and into the gonadal (Genital) ridge

12. Gonad and relation to gonadal Ducts

13. Development of Gonad
Source Male (Testis) Female (Ovary)
Genital ridge fibrous septa,
tunica albuginea
and Interstitial
cells of Leydig
Capsule and
stroma
Coelomic
epithelium
Seminiferous
tubules and Sertoli
cells
Follicular cells
Primordium Germ
cells
Spermatozoa Ovum

15. Descend of the testis from lumbar region to scrotum
At 3rd month at iliac fossa At 7th month at inguinal canal
At 8th month at superficial inguinal ring
At 9th month at scrotum

16. Causes of Descend of testis:
-Elongation of upper part of posterior abdominal wall.
-Growth of abdominal viscera.
-Contraction of gubernaculum under effect of gonadotrophins.
-Congenital Anomalies:
1- Cryptorchism: failure of descend.
2- Ectopic testis: mal-descend of testis.
3- Congenital inguinal hernia: persistence of processus
vaginalis.
4- Congenital cyst of spermatic cord: persistence of
unobliterated part of processus vaginalis.

18. Descent of the ovary:
-From Lumbar region to pelvic cavity
-Remnant of Gubernaculum:
•from ovary to uterus form ovarian ligament
•from uterus to labia majora forms round ligament of uterus
Congenital Anomalies:
1- Ovarian agenesis: failure of formation.
2- Ovarian hypoplasia: low number of primordial follicles.
3- Maldescended ovary: Ovary in abnormal site.

19. Derivatives of Genital ducts and
relation to urogenital sinus
Source Male Female
Mesonephric tubules Vasa efferentia Epoophoron and
Paroopharon
Mesonephric duct
(Wolfian Duct)
Epididymis, vas
deferens, seminal
vesicle, ejaculatory
duct, Collecting part of
ureter and trigone of
urinary bladder
Most of the duct
disappear. Duct of
Epoophoron (Duct of
Gartner), Collecting
part of ureter and
trigone of urinary
bladder
Paramesonephric duct
(Mullerian Duct)
Most of the duct
disappear.
Forms prostatic utricle
Fallopian tubes,
Uterus and upper part
of vagina
Mesonephric ducts opens in Urogenital sinus. Hence ureter opens in
bladder and ejaculatory duct open in prostatic urethra

31. Congenital Anomalies
 1- Persistence of intrauterine septum.
 2- Double uterus & double vagina: due to failure
of fusion between the 2 ducts.
 3- Bicornuate uterus: due incomplete fusion of the
ducts.
 4- Rudimentary horn: Failure of formation of one
duct.
 5- Atresia of cervix or vagina: failure of
canalization.
 6- Imperforate hymen: due to failure of
perforation.

33. Development of External
Genitalia
Source Male Female
Genital tubercle Phalus (Penis) Clitoris
Genital folds Urethral folds fuse
to form penile
urethra
Labia Minora
Genital swellings Fuse to form
scrotum
Labia Majora

37. CONGENITAL ANOMALIES
 1- Hypospadius: Opening of urethera on lower
surface of penis due to failure of fusion of uretheral
folds.
 2- Clitoris hypertrophy: overgrowth of genital
tubercle.
 3- Undersized penis: undergrowth of genital tubercle.
 4- Bifid scrotum: failure of fusion of genital swellings.
 5- Pseudohermaphrodite: External genitalia belong
to one sex and the gonads belong to the other.

43. Complet gonadal dysgenesis
Swyer syndrome
 Bilateral streak gonads
 Apparently normal female
external genitalia
 High risk of
gonadoblastoma, germinoma
 Karyotype: 46,XY

47. Anatomical situation in a patient with Mayer-
Rokitanski-Kuster
 Mayer-Rokitansky-Kuster-Hauser (MRKH)
syndrome consists of vaginal aplasia with other
müllerian (ie, paramesonephric) duct abnormalities.
 Surgical correction of the vaginal anomaly permits
normal sexual function and, possibly, reproduction
with assisted techniques.

49. Summary
 Sexual differentiation is dependent on
SRY gene followed by TDF and Mullerian
Inhibiting Factor (MIF).
 46 XX: Female, 46 XY, Male
 Wolfian duct forms male genital structures
 Mullerian duct form female genital
strcutures
 Genetic defects can lead to Gonadal
dysgenesis

50. Quiz
 List two structures derived from
Mesonephric duct.
 List two structures derived from
Paramesonephric duct.
 Mention two uterine anomalies.
 What is cause of congenital adrenal
hyperplasia?

51. …..Thanks…..