Calretinin and calbindin D28K immunoreactivity in the superficial layers of the rabbit superior colliculus

CALRETININ and calbindin D28K were localized in the superficial layers of r abbit superior colliculus (SC). Calretinin and calbindin D28K-immunoreactiv e (-IR) neurons were concentrated in the upper superficial gray layer. Calr etinin-IR fibers were found in the optic layer. The majority of calretinin- IR cells were small- to medium-sized vertical fusiform neurons and neurons with round or stellate-shaped somas with small varicose dendrites. The morp hology of calbindin D28 K-IR neurons was different from that of calretinin neurons. Anti-calbindin D28K-IR neurons usually had fusiform cell bodies an d a thick primary dendrite with small branches forming a dendritic bouquet. Two-color immunofluorescence revealed that no cells expressed both protein s. Following unilateral enucleation a marked reduction of calretinin-IR fib ers in the contralateral side to the enucleation was found. Enucleation app eared to have no effect on the cell bodies labeled with either protein. The results suggest the anti-calretinin immunoreactivity in the superficial la yer of rabbit SC contrasts starkly with that of other animals. NeuroReport 9: 3847-3852 (C) 1998 Lippincott Williams & Wilkins.