520 Obstetrics and Gynecology Board Review •••
❍ What role does GnRH have on the anterior pituitary?
Stimulate release of gonadotrophs: luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
❍ Constant infusion on GnRH has what effect on circulating gonadotrophs?
Initial increase in both LH and FSH (flare), followed by an inhibition of release for 1 to 3 weeks, called
desensitization or downregulation.
❍ What is an important side effect of GnRH agonists?
Decrease in bone mineral density.
❍ Where do axons from the supraoptic and paraventricular nuclei of the hypothalamus terminate?
The posterior pituitary or neural lobe.
❍ What hormones are synthesized from the supraoptic and paraventricular nuclei?
Antidiuretic hormone (ADH) and oxytocin precursors.
❍ What syndrome results from absence of the axonal and GnRH neuronal migration from the olfactory
placode?
Kallmann syndrome (hypogonadotropic hypogonadism).
❍ What are the modes of transmission of Kallmann syndrome?
X-linked, autosomal dominant, and autosomal recessive.
❍ What are the characteristics of Kallmann syndrome?
Absence of secondary sexual development, amenorrhea, lack of GnRH, and anosmia.
❍ What is the treatment of Kallaman syndrome?
Exogenous GnRH.
❍ What are the nonendocrine functions of the hypothalamus?
Temperature regulation, the activity of the autonomic nervous system, and control of appetite.
PITUITARY
❍ Where is the hypophysis (pituitary gland) located?
Within the sella turcica.
❍ What is the blood supply to the posterior lobe of the pituitary gland?
The inferior hypophyseal artery, a branch from the carotid artery.
❍ Who has the larger pituitary gland, men or women?
The average adult female gland is approximately 20% larger than the average adult male.