20 Obstetrics and Gynecology Board Review •••
❍ What is the origin of the clitoris?
The genital tubercle. In the female the genital tubercle elongates only slightly resulting in the clitoris.
❍ What is the origin of the labia minora?
Urethral folds.
❍ What is the gubernaculum testis?
The gubernaculum testis is the column of mesenchyme that extends from the caudal pole of the testis to the
genital swelling.
❍ Is the descent of the testis under any hormonal influence?
Yes. The descent of the testis is influenced by androgens and gonadotropins.
❍ The proliferation of the sinovaginal bulbs results in what portion of the female genital tract?
Lower third of the vagina.
❍ What is androgen insensitivity syndrome (testicular feminization)?
X-linked recessive, 46XY genotype, and female phenotype (male pseudohermaphroditism).
❍ What is the pathophysiology of androgen insensitivity syndrome?
Androgen receptors are absent or defective. There is normal fetal production of testosterone and AMH. Since
receptors are defective, fetal androgens are unable to cause male external genitalia formation. Production of AMH
results in absence of Müllerian structures (absent fallopian tubes, uterus and upper vagina). A small vagina with a
blind end pouch may be present.
❍ What are the clinical manifestations?
Presents as primary amenorrhea. Some estrogen production results in breast development. There will be absent or
sparse axillary and pubic hair. Testes will be present either in labia or inguinal canal and should be removed after
puberty secondary to risk of malignancy.
❍ Should the testes in patients with testicular feminization be surgically removed?
Yes. The testes in these patients are at increased risk of developing tumors. The recommendation is for removal
following puberty between 16 and 18 years.
❍ What other condition besides androgen insensitivity syndrome gives rise to external female phenotype but
absent Müllerian development?
Müllerian agenesis (Mayer-Rokitansky-Küster-Hauser syndrome).
❍ How do you differentiate between androgen insensitivity and Müllerian agenesis?
In Müllerian agenesis, ovaries are present; therefore secondary sexual characteristics will develop normally. A
karyotype will reveal that patients with Müllerian agenesis are 46XX.