Chapter 15 - Male Reproductive System

Question 1

One day a 9-year-old girl surprisingly
announces to her mother, “Guess what,
mommy, I’m not a girl; I’m a boy.” The mother
is shocked but does act on the comment.
During the next few years, the mother
notices some tomboyish behavior and difficulty
in social adjustment at school. When
the girl is 12 years old, puberty starts with a
striking virilization of the external genitalia.
The mother is extremely concerned and
seeks medical attention. What is the most
likely cause?

(A) Male pseudo-intersexuality
(B) Female pseudo-intersexuality
(C) Congenital adrenal hyperplasia
(D) Testicular feminization
(E) Illegal use of anabolic steroids

Answer 1

A. Male pseudo-intersexuality

Reduced levels of androgens during fetal development of an XY male fetus cause a feminization of the male external genitalia such that the baby can be phenotypically mistaken
for female. Parents raise the XY male baby as a girl until puberty or other medical problems
bring the child to medical attention.

Question 2

The most common cause of female
pseudo-intersexuality is

(A) a 46,XO genotype
(B) a 47,XXY genotype
(C) lack of androgen receptors
(D) congenital adrenal hyperplasia
(E) inadequate production of testosterone
and Müllerian-inhibiting factor (MIF)

Answer 2

D. Congenital adrenal hyperplasia

Female pseudo-intersex individuals have a 46,XX genotype. This condition is most commonly
caused by congenital adrenal hyperplasia, in which the fetus produces excessive
amounts of androgens. The high androgen level will masculinize the female genitalia.

Question 3

The most common cause of male pseudointersexuality is

(A) a 45,XO genotype
(B) a 47,XXY genotype
(C) inadequate production of testosterone
and MIF
(D) congenital adrenal hyperplasia
(E) lack of androgen receptors

Answer 3

C. Inadequate production of testosterone and MIF

Male pseudo-intersex individuals have a 46,XY genotype. This condition is most
commonly caused by inadequate production of testosterone and MIF by the fetal testes.
The low testosterone and MIF levels will stunt the development of the male genitalia.

Question 4

The most common cause of testicular
feminization syndrome is

(A) a 45,XO genotype
(B) a 47,XXY genotype
(C) inadequate production of testosterone
and MIF
(D) congenital adrenal hyperplasia
(E) lack of androgen receptors

Answer 4

E. Lack of androgen receptors

The most common cause of testicular feminization syndrome is the lack of androgen
receptors in the urogenital folds and labioscrotal swellings. Because these tissues lack
androgen receptors, they are blind or unresponsive to androgens. Consequently, these
tissues develop into female external genitalia even though the fetus has a 46,XY genotype.

Question 5

In the male, failure of the urethral folds to
fuse completely results in

(A) hypospadias
(B) epispadias
(C) cryptorchidism
(D) congenital inguinal hernia
(E) hydrocele

Answer 5

A. Hypospadias

Failure of the urethral folds to fuse completely results in the external urethral orifice
opening onto the ventral surface of the penis, a condition known as hypospadias.

Question 6

The Y chromosome carries a gene on its
short arm that codes for

(A) testosterone
(B) MIF
(C) testes-determining factor (TDF)
(D) progesterone
(E) estrogen

Answer 6

C. Testes - determining factor (TDF)

The gene product that is coded on the short arm of the Y chromosome is called the
testes-determining factor (TDF).

Question 7

Bilateral cryptorchidism usually results in

(A) impotence
(B) sterility
(C) male pseudo-intersexuality
(D) female pseudo-intersexuality
(E) testicular feminization syndrome

Answer 7

B. Sterility

Sterility is a common result of bilateral cryptorchidism. When both testes fail to
descend into the scrotum, the increased temperature to which they are exposed in the
abdominal cavity will inhibit spermatogenesis.

Question 8

A 17-year-old girl presents with a
complaint of amenorrhea. Physical
examination reveals good breast
development and normal amount of pubic
hair. A rudimentary vagina and a mobile
mass within both the right and left labia
majora are found on pelvic examination.
Ultrasound reveals the absence of a uterus.
What is the diagnosis?

(A) Testicular feminization syndrome
(B) Gonadal dysgenesis
(C) Cryptorchidism
(D) Female pseudo-intersexuality
(E) Hypospadias

Answer 8

A. Testicular feminization syndrome

This is a classic case of testicular feminization syndrome. A karyotype analysis would
reveal that this normal-appearing 17-year-old girl actually has a 46,XY genotype. The mobile
masses within the right and left labia majora are the testes and should be surgically removed
because this tissue has a propensity toward malignant tumor formation. The most common
cause of this syndrome is a lack of androgen receptors in the phallus, urogenital folds, and
labioscrotal swellings.