The distribution of luteinizing hormone-releasing hormone (LHRH) neurons and fibers in the Formosan rock-monkey

The anatomical distribution of neurons and fibers containing Luteinizing Hormone Releasing Hormone-Immunoreactivity (LHRH-IR) in the brain of the Formosan Rock-Monkey was investigated employing immunohistochemical techniques. LHRH-IR neurons were observed in an area demarcated rostrally by the diagonal band of Broca and caudally by the mammillary area. The majority of these neurons were principally localized in the preoptic area, periventricular zone, and the arcuate nucleus. The supraoptic nucleus, septal area, triangular septal nucleus, nucleus of the diagonal band of Broca, suprachiasmatic nucleus, retrochiasmatic area, mammillary area, and the amygdala also exhibited neuronal LHRH immunoreactivity. LHRH-IR fibers appeared to originate in all of the above areas of the hypothalamus, project caudally, and subsequently terminate in the median eminence (ME). In addition to the above, LHRH-IR fibers were also detected in the organum vasculosum of the lamina terminalis (OVLT). A scattering of LHRH-IR fibers were also observed in several extrahypothalamic regions, notably the subfornical organ, indusium griseum, habenular complex, septohypothalamic nucleus, and amygdala.