16.2 Development of the Male External Genitalia

Question 1

Indifferent Stage

The development of the external genitalia begins in the

Answer 1

3rd week

Question 2

Mesenchymal cells from the primitive streak migrate to the cloacal membrane to form a pair of

Answer 2

clocal folds

Question 3

Cranially, these clocal folds fuse to form the

Answer 3

genital tubercle

Question 4

genital tubercle

- Caudally, they divide into

Answer 4

urethral folds (anterior) and anal folds (posterior).

Question 5

Genital swellings develop either side of the

Answer 5

urethral folds

Question 6

The development of the indifferent genitalia into the male genitalia is driven by the presence of androgens from the testes, namely

Answer 6

dihydrotestosterone (DHT)

Question 7

There is rapid elongation of the genital tubercle, which becomes the

Answer 7

phallus

Question 8

The urethral folds are pulled to form the ______ – this extends along the caudal aspect of the phallus.

Answer 8

urethral groove

Question 9

The urethral folds close over by the ____ month, forming the penile urethra.

Answer 9

4th

Question 10

become the scrotal swellings, moving caudally to eventually form the scrotum.

Answer 10

genital swellings

Question 11

A condition in which there are one or more abnormal openings of the urethra along the inferior side of the penis. This is a result of incomplete closure of the urethral folds during development. Surgery is usually performed to correct the defect.

Answer 11

Hypospadias

Question 12

phallus enlarges and elongates to form

Answer 12

penis
corpora cavernosa
corpora spongiosum

Question 13

form ventral aspect of penis and spongy urethra

Answer 13

urogenital folds