Normal Prenatal Gender Differentiation

Question 1

Genetic Gender

Answer 1

Begins at conception (union of sperm and egg); XX is a genetic female; XY is a genetic male;

Question 2

Gonadal Gender

Answer 2

Occurs about 6 to 8 weeks after conception; H-Y Antigen: found on the X chromosome, causes the undifferentiated gonads to develop into testicles, if there’s no Y chromosome, the gonads will develop into ovaries

Question 3

Hormonal Gender*

Answer 3

Occurs about 8 to 10 weeks after conception; Testicles manufacture *testosterone–> furthers development of internal reproductive system, and MIS (Mullerian Inhibiting Substance); Testosterone promotes development of the * Wolffian duct system (forms the epididymis, vas deferens, and seminal vesicles); MIS inhibits growth and development of the *Mullerian Duct system ( forms the fallopian tubes, uterus, cervix, and possibly upper part of the vagina); *Both testosterone and MIS must be present for normal development of the male internal reproductive structures; If either testosterone or MIS is missing, or the testicles are removed during this critical embryonic period, the embryo will develop as a female, even if it is genetically XY

Question 4

Genital Gender

Answer 4

Occurs by the end of the 12th week after conception; for the development of the male external genitalia, testosterone is converted to a more potent substance, dihydrotestosterone (DHT); development of the female external genitalia occurs in the absence of male hormones