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The anterior pituitary (also called the adenohypophysis or pars anterior) is a major organ of the endocrine system.The anterior pituitary is the glandular, anterior lobe that together with the (posterior pituitary, or the neurohypophysis) makes up the pituitary gland (hypophysis) which, in humans, is located at the base of the brain, protruding off the bottom of the hypothalamus.
The hypophyseal portal system is a system of blood vessels in the microcirculation at the base of the brain, connecting the hypothalamus with the anterior pituitary. Its main function is to quickly transport and exchange hormones between the hypothalamus arcuate nucleus and anterior pituitary gland.
General diagram of a portal venous system, for example, this occurs in the hypophyseal portal system between the hypothalamus and the anterior pituitary gland. In the circulatory system of vertebrates, a portal venous system occurs when a capillary bed pools into another capillary bed through veins, without first going through the heart. Both ...
Endocrine cells of the anterior pituitary are controlled by regulatory hormones released by parvocellular neurosecretory cells in the hypothalamic capillaries leading to infundibular blood vessels, which in turn lead to a second capillary bed in the anterior pituitary. This vascular relationship constitutes the hypophyseal portal system.
HPG regulation in males, with the inhibin/activin system playing a similar role on GnRH-producing cells. The hypothalamus is located in the brain and secretes GnRH. [1] GnRH travels down the anterior portion of the pituitary via the hypophyseal portal system and binds to receptors on the secretory cells of the adenohypophysis. [2]
The pituitary gland is divided into three lobes: the anterior pituitary, the intermediate pituitary lobe, and the posterior pituitary. The hypothalamus controls the anterior pituitary's hormone secretion by sending releasing factors, called tropic hormones, down the hypothalamo-hypophysial portal system. [3]
The pouch eventually loses its connection with the pharynx giving rise to the anterior pituitary. The anterior wall of Rathke's pouch proliferates, filling most of the pouch to form pars distalis and pars tuberalis. The posterior wall forms pars intermedia. In some organisms, the proliferating anterior wall does not fully occupy Rathke's pouch ...
The release of ACTH from the corticotropic cells is controlled by CRH, which is formed in the cell bodies of parvocellular neurosecretory cells within the paraventricular nucleus of the hypothalamus and passes to the corticotropes in the anterior pituitary via the hypophyseal portal system.