Figure 3.

Images of labeled tectoincertal and incertotectal elements in the gray squirrel. A. Appearance of ZI following an injection of WGA-HRP into the SC. Note the band of terminals in the upper part of the dorsal layer of ZI (dZI) and the band of labeled cells filling the ventral layer of ZI (vZI). Box indicates the region shown at higher magnification in B, where the multipolar nature of the incertotectal cells in vZI can be appreciated. In addition, the scattered, more lightly labeled, cells in dZI are indicated by arrowheads. C. Numerous scattered puncta are present in the lower sublamina of the intermediate gray layer (lSGI) of the squirrel following an injection of WGA-HRP into the zona incerta (see Fig. 6). Retrogradely labeled tectoincertal cells (arrowheads) are also present. Relatively little label is seen in either the upper sublamina of SGI (uSGI) or the intermediate white layer (SAI). D. The dendritic morphology of incertotectal cells is evident following injections of HRP in saponin into the SC. Images A–C were taken with crossed polarizers. Scale in C = A, in D = B.