Pharmacology of Adenohypophyseal Hormones
The modulation of anterior pituitary hormone secretion relies on the release of hypothalamic substances into the capillaries of the median eminence. The anatomical relationship between the hypothalamus and the anterior pituitary gland consists of a rather complex vascular network (Figure 2–1). The hypothalamus is adjacent to the pituitary stalk, and the general anatomical region is referred to as the median eminence. The pituitary stalk connects the hypothalamus to the adenohypophysis. A system of portal veins extending along the pituitary stalk serves as a connecting link of capillary plexuses in the median eminence and in the adenohypophysis. Most of the blood flowing into the adenohypophysis has initially traversed the capillary system situated in the median eminence region of the hypothalamus. A major portion of the blood supply to the anterior pituitary gland is derived from the superior hypophyseal arteries via the hypothalamus. Terminal arterioles from the superior hypophyseal arteries form a capillary network in the area of the median eminence of the hypothalamus. This portal system connecting the hypothalamus and adenohypophysis transports the hypophysiotrophic hormones from the median eminence to the anterior pituitary gland.
KeywordsGrowth Hormone Luteinizing Hormone Median Eminence Pituitary Stalk Anterior Pituitary Hormone
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