Releasing and inhibiting hormones Releasing and inhibiting hormones Releasing hormones and inhibiting hormones are hormones whose main purpose is to control the release of other hormones, either by stimulating or inhibiting their release. They are also called liberins () and statins () (respectively), or releasing factors and inhibiting factors. The examples are hypothalamic-pituitary hormones that can be classified from several viewpoints: they are hypothalamic hormones (originating in the hypothalamus), they are hypophysiotropic hormones (affecting the hypophysis, that is, the pituitary gland), and they are tropic hormones (having other endocrine glands as their target). For example, thyrotropin-releasing hormone (TRH) is released from the hypothalamus in
Pituitary gland often not clearly marked. In elasmobranchs there is an additional, "ventral lobe" beneath the anterior pituitary proper. The arrangement in lampreys, which are among the most primitive of all fish, may indicate how the pituitary originally evolved in ancestral vertebrates. Here, the posterior pituitary is a simple flat sheet of tissue at the base of the brain, and there is no pituitary stalk. Rathke's pouch remains open to the outside, close to the nasal openings. Closely associated with the pouch are three distinct clusters of glandular tissue, corresponding to the intermediate lobe, and the rostral and proximal portions of the