Distribution of calbindin, parvalbumin and calretinin in the lateral geniculate nucleus and superior colliculus in Cebus apella monkeys

We studied the distribution of the calcium-binding proteins calbindin, parv albumin and calretinin, in the superior colliculus and in the lateral genic ulate nucleus of Cebus apella, a diurnal New World monkey. In the superior colliculus, these calcium-binding proteins show different distribution patt erns throughout the layers. After reaction for calretinin one observes a he avy staining of the neuropil with few labeled cells in superficial layers, a greater number of large and medium-sized cells in the stratum griseum int ermediate, and small neurons in deep layers. The reaction for calbindin rev ealed a strong staining of neuropil with a large number of small and well s tained cells, mainly in the upper half of the stratum griseum superficiale. Intermediate layers were more weakly stained and depicted few neurons. The re were few immunopositive cells and little neuropil staining in deep layer s. The reaction for parvalbumin showed small and medium-sized neurons in th e superficial layers, a predominance of large stellate cells in the stratum griseum intermediate, and medium-sized cells in the deep layers. In the la teral geniculate nucleus of Cebus, parvalbumin is found in the cells of bot h the P and M pathways, whereas calbindin is mainly found in the interlamin ar and S layers, which are part of the third visual pathway. Calretinin was only found in cells located in layer S. This pattern is similar to that ob served in Macaca, showing that these calcium-binding proteins reveal differ ent components of the parallel visual pathways both in New and Old World mo nkeys. (C) 2001 Elsevier Science B.V. All rights reserved.