Immunohistochemical localization of luteinizing hormone-releasing hormone in the rat median eminence

Although it has been shown that hypothalamic neurohormones controlling adenohypophyseal activity are concentrated in the median eminence, precise identification of the intracellular structures containing hypophysiotropic hormones has as yet not been achieved. Using an immunohistochemical technique at the electron microscopic level, it was observed that luteinizing hormone releasing hormone (LH-RH), the neurohormone stimulating the release of both FSH and LH, is contained in the secretory granules of some nerve endings located in the palisade layer of the median eminence. This is the first demonstration at the ultrastructural level that an hypothalamic releasing hormone is stored in secretory granules of the median eminence.