Obstetrics and Gynecology

Question 1

Is it possible to to determine sex on appearance during the first trimester?

Answer 1

No through the first trimester the fetal gonads, genital ducts and genitalia are differentiated and is therefore not possible to determine sex on appearance

Question 2

What determines the sex of an individual?

Answer 2

It is determined by the sperm being either X or Y.

Question 3

How does the Y chromosome cause development of a male?

Answer 3

Through the SRY (sex determining gene on Y) which encodes the testis determining factor. (TDF)

Question 4

How does the X chromosome from the male cause development of a female?

Answer 4

Through the WNT4 gene which is the ovarian development gene.

Question 5

At what stage of development are the gonads able to differentiated as male or female?

Answer 5

By week 7

Question 6

At what stage of development are the external genetalia able to differentiated as male or female?

Answer 6

By week 12

Question 7

What influences external genitalia development?

Answer 7

Through the influence of androgens. Androgens are crucial for the development of the male external genitalia. However excess of androgens in females causes ambiguity in female genitalia.

Question 8

At what week does the primordial germ cells start migrating through the Allantois into the genital ridges?

Answer 8

By week 3 genital ridges arise along the posterior wall of the coelomic cavity and the germ cells start migrating into the genital ridges.

Question 9

The development of the primordial germ cells

Answer 9

3rd week they are found in the yolk sac and have begun migration into the genital ridge
5th week they migrate along the allantois to reach the gonadal ridges
6th week they are associated with the primary sex cords

Question 10

The development of the primordial germ cells in the female ovary

Answer 10

The primordial germ cells become oogonia via numerous mitotic divisions. They then undergo the first meiotic division to become the primary oocyte. Here they arrest at this stage until puberty.

Question 11

The primary sex cords in ovarian development

Answer 11

The primary sex cords degenerate and secondary/cortical cords form and surround each primary oocyte. The cord and the oocyte together are known as the primordial follicle

Question 12

What is the function of the gubernaculum in female develop ment

Answer 12

The gubernaculum is a messenchymal condensation which is attached to the caudal end of the genital. It supports the ovaries descent into the pelvis. It then forms the adult ovarian and round ligaments

Question 13

The development of the primary sex cords in the male

Answer 13

The primary sex cords develop to form the seminiferous cords which further develop into rete testis and seminiferous tubules

Question 14

What is the function of the gubernaculum in male development?

Answer 14

Supports the descent of the testis into the developing scrotum which then becomes the adult scrotal ligament holding the testis in place.

Question 15

During the genital duct development there are 2 pairs of ducts which are present what are they and what are they responsible for?

Answer 15

The 2 ducts are the mesonephric (Wolffian) and the paramesonephric (Mullerian).
The mesonephric is responsible for male genital tracts while the paramesonephric ducts is reponsible for the formation of the female genital tracts.

Question 16

What is the key hormone responsible for the picking of which duct to develop?

Answer 16

The anti-mullerian hormone which is secreted by the sertoli cells of the testis. The AMH is responsible for the inhibition of the paramesonephric development. Therefore by default we are all females)

Question 17

What is a gartner duct cysts?

Answer 17

Cyst that can from in the side walls of the vagina. They are reminants of the mesonephric ducts that did not completely regress during deveopment.