Localization of FMRFamide-like immunoreactivity in the brain of the viviparous skink (Chalcides chalcides)

Neuroanatomical distribution of FMRFamide-like immunoreactivity was investi gated in the brain and olfactory system of the viviparous skink, Chalcides chalcides. In the adult brain FMRFamide immunoreactive (ir) perikarya were observed in the diagonal band of Broca, medial septal nucleus, accumbens nu cleus, bed nucleus of the anterior commissure, periventricular hypothalamic nucleus, lateral forebrain bundle, and lateral preoptic, subcommissural, s uprachiasmatic and lateral hypothalamic areas. This pattern was seen in bot h male and female brains. Though all major brain areas showed FMRFamide-ir innervation, the densest ir fiber network was observed in the hypothalamus. During development, ir elements were observed for the first time in embryo s at mid-pregnancy. FMRFamide perikarya were located along the ventral surf ace of the vomeronasal nerve, in the olfactory peduncle mediobasally, as we ll as in the anterior olfactory nucleus and olfactory tubercle. Furthermore , some ir neurons were observed in the rhombencephalic reticular substance; however, the ir fiber network was poorly developed. Later in development F MRFamide-ir neurons appeared also in the bed nucleus of the anterior commis sure as well as the rhombencephalic nucleus of solitary tract and the dorsa l motor nucleus of vagus nerve. In juveniles, the distribution profile of F MRFamide immunoreactivity was substantially similar to that of the adults, with a less widespread neuronal distribution and a more developed fiber net work. Ontogenetic presence of FMRFamide immunoreactivity in the nasal area has been linked to the presence of a nervus terminalis in this reptile, Cop yright (C) 2001 S. Karger AG. Basel.