1 - Repro - Origin of the Sexes

Question 1

From which layer of the bilaminar disc does do the primordial germ cells develop from?

Answer 1

Epiblast

Question 2

What determines whether the primordial gonads develop into ovaries or testes?

Answer 2

Whether they are colonised by a germ cell with XX or XY chromosomes

Question 3

What part of the primordial gonad does a germ cell with XX chromosomes colonise?

Answer 3

Cortex

Question 4

What part of the primordial gonad does a germ cell with XY chromosomes colonise?

Answer 4

Medulla

Question 5

Name the gene expressed by Sertoli cells, which drives male development:

Answer 5

SRY gene

Question 6

Which cell expresses the SRY gene which drives Male development?

Answer 6

Sertoli cells

Question 7

What is the average length of the vas deferens?

Answer 7

~ 30-45 cm

Question 8

Which part of the male genitalia develops from the urogenital sinus?

Answer 8

Prostate
Bulbourethral glands
Urethra

Question 9

Which part of the male genitalia develops from the mesonephric duct?

Answer 9

Epidydimis
Vas deferens
Seminal vesicles

Question 10

Which part of the female genitalia develops from the urogenital sinus?

Answer 10

Vagina

Question 11

Which part of the female genitalia develops from the paramesonephric ducts?

Answer 11

Fallopian tubes
Uterus
Cervix

Question 12

List some secondary female sex characteristics:

Answer 12

• Hair growth
• Breast development
• Subcutaneous fat redistribution (around hips, buttocks and thighs)
• Elbows hyperextend 5-8’ more than males

Question 13

List some male secondary sex characteristics:

Answer 13

• Hair growth
• Change in body composition: more muscle:fat
• Enlargement of larynx = voice deepens
• Larger hands, feet and nose
• Broadening of shoulders and chest

Question 14

What is another name for the Wolffian ducts?

Answer 14

Mesonephric ducts

Question 15

What is another name for the Mullerian ducts?

Answer 15

Paramesonephric ducts

Question 16

Name the ducts from which the male genitalia develop from:

Answer 16

Mesonephric/Wolffian ducts

Question 17

Name the ducts from which the female genitalia develop from:

Answer 17

Paramesonephric/Mullerian ducts

Question 18

What ensures the regression of the Mullerian ducts for male development?

Answer 18

Mullerian Inhibitory Hormone (MIH) release from Sertoli cells

Question 19

What substance is secreted by Sertoli cells causing the regression of the Mullerian ducts?

Answer 19

Mullerian Inhibitory Hormone (MIH)

Question 20

What substance supports the development of the Mesonephric/Wolffian ducts?

Answer 20

Androgens

Question 21

Name the parts of the external genitalia of an indifferent embryo:

Answer 21

• Genital tubercle
• Genital swelling
• Genital fold
• Urethral fold

Question 22

What parts of the female external genitalia form from the urethral folds and genital swelling?

Answer 22

Labia minora

Labia majora

Question 23

What part of the female external genitalia form from the genital tubercle?

Answer 23

Clitoris

Question 24

Which hormone is vital for the closing of the urethral folds, for the development of the penis?

Answer 24

Dihydrotestosterone

Question 25

Which part of the male external genitalia form from the genital swelling?

Answer 25

Testes

Question 26

Which part of the male external genitalia form from the genital tubercle?

Answer 26

Glans penis

Question 27

Name the remnant of the gubernaculum:

Answer 27

``` Males = Scrotal ligament Females = Round ligament of the uterus + Ovarian ligament ```

Question 28

Describe the location from where the testes and ovaries arise:

Answer 28

Upper lumbar area of posterior abdominal wall

Question 29

In approx. which month of development do the testes reach the iliac fossa?

Answer 29

~ 3rd month

Question 30

In approx. which month of development do the testes enter the inguinal canal?

Answer 30

~ 7th month