Immunocytochemical localization of calcium-binding protein calretinin containing neurons in cat visual cortex

The distribution and morphology of neurons containing calretinin in area 17 of the cat visual cortex were studied. The calcium-binding protein calretinin was localized by antibody immunocytochemistry. Most of the calretinin-labeled neurons were located in layers I, II, and III. There were few calretinin-labeled cells in the other layers. The labeled neurons varied in morphology. The majority of the labeled neurons had small round or oval somas with long processes traveling perpendicular to the pial surface. Many small multipolar neurons were also labeled by this antibody. These results indicate that the calcium-binding protein calretinin is contained both in specific layers and selective cell types in the cat primary visual cortex.