Role of the hypophyseal neurointermediate lobe in the dynamic release of prolactin.
The dynamic release of prolactin (PRL) occurs in a region of the anterior pituitary lobe (AP) that receives its blood supply primarily from the hypophyseal neurointermediate lobe (NIL) via the short portal vessels. This relationship, coupled with a growing body of supportive evidence, suggests that the hypophysiotropic signal mediating the massive discharge o f AP PRL derives from the NIL rather than the hypothalamic median eminence, as previously believed. Moreover, a major component of this signal appears to be a-MSH.
Stephen Frawley
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Department of Cell Biology and Anatomy, Medical University of South Carolina, Charleston, SC 29425, USA.