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5. What are the factors responsible for sex determination?

Sex determination is an active process wherein a bipotential gonad develops into

testis or ovary. The development of bipotential gonad into testis initiates at 6–7 weeks

of intrauterine life and is determined by genes like SRY , SOX9 , SF1 , WT1 , and

DHH. Expression of SRY gene (Yp11.3) initiates the development of testis by regu-

lating multiple downstream sex-determining factors including SOX9. The develop-

ment of ovary from bipotential gonad is not a passive process, as believed previously

and the genes determining ovarian development include WNT4 , FOXL2 and

RSPO1.

6. What is the importance of DAX1 in sex determination?

DAX1 (dosage-sensitive sex reversal adrenal hypoplasia congenita critical

region on the X chromosome, gene 1) located on Xp20.3 is necessary for the

development of testes/ovaries, hypothalamus, and pituitary gland (GnRH–

gonadotropin–gonadal axis) and adrenal cortex. As the name suggest, DAX1 is

a dose-dependent gene and plays an important role in sex determination.

Expression of one copy of DAX1 facilitates the development of bipotential

gonad into testis/ovary as determined by the chromosomal sex. Deletion or

inactivating mutation of DAX1 is associated with hypogonadotropic

hypogonadism and congenital adrenal hypoplasia, whereas duplication of

DAX1 results in gonadal dysgenesis.

7. What are the derivatives of Wolffi an duct and Mullerian duct in males and females?

The derivatives of Wolffi an duct and Mullerian duct in male and female are

summarized in the table given below.

Male Female

Wolffi an duct Epididymis

Vas deferens

Seminal vesicle

Ejaculatory duct

Ureter

Renal pelvis and calyces

Collecting ducts

Ureter

Renal pelvis and calyces

Collecting ducts

Gartner’s duct

Mullerian duct Appendix testis

Utricle of prostate

Fallopian tubes

Uterus and cervix

Upper two-thirds of vagina

9 Disorders of Sex Development