Gonadotropin-Releasing Hormone (GnRH) Neuron in the Forebrain of Male Shiba Goat.

The GnRH neuron was investigated immunohistochemically in the hypothalamus and other diencephalic areas of mature male Shiba goats. Morphological characteristics and the distri-bution pattern of cell bodies immunoreactive to GnRH (GnRH-ir) as well as the projection of GnRH-ir fibers were examined in serial coronal sections (40 μm thick) extending from the diagonal band of Broca to the mammillary complex in the rostro-caudal direction using a specific mono-clonal antibody (LRH 13). The GnRH-ir cell bodies were classified morphologically into two sub-types, i.e. bipolar and multipolar, based on the number of processes. The distribution pattern of GnRH-ir cell bodies was strikingly similar in all the animals examined, and 51% of total immunore-active neurons were found in a restricted region including the preoptic area, supraoptic nuclei and the vicinity of the organum vasculosum of the lamina terminalis. The major fiber projections were seen in the neurohemal organs, namely the median eminence and the organum vasculosum of the lamina terminalis. The GnRH fibers were also found in the mammillary complex and the habenular system but not in the amygdaloid complex.