Distribution of calcium-binding proteins in the chick visual system.

The calcium-binding proteins calbindin (CB), calretinin (CR), and parvalbumin (PV) have been extensively studied over the last decade since they appear to be important as buffers of intracellular calcium. In the present study we investigated the distribution of these proteins in the chick visual system by means of conventional immunocytochemistry. The results indicated that CB, CR, and PV are widely distributed in retinorecipient areas of the chick brain. In some regions, all three calcium-binding proteins were present at different intensities and often in different neurons such as in the dorsolateral thalamic complex. In other areas, such as the nucleus geniculatus lateralis ventralis, only CB and CR were detected, whereas PV was absent. These results show that these three calcium-binding proteins are differentially distributed in the visual system of the chick, with varying degrees of co-localization.