Abstract
It is firmly established that the secretory activity of the pituitary gland is regulated by the hypothalamus of the brain by means of the releasing and inhibiting hormones which are elaborated by the nerve cells in the hypothalamus and transported to the pituitary via the hypophyseal portal vessels. The secretion of each of the six adenohypophyseal hormones (ACTH, TSH, LH, FSH, GH, and prolactin) and the hormone of the intermediate lobe of pituitary (MSH) is controlled by the respective hypothalamic regulating hormone(s). The release of ACTH, TSH, LH, FSH, and GH is under the control of stimulatory influence of the releasing hormones, whereas the secretion of prolactin and MSH is mainly under a tonic control by the inhibitory hormones. In addition, the secretion of prolactin and MSH appears to be regulated by their releasing hormones, and GH by the release-inhibiting hormone (Schally et al., 1973a).