Fig. 10.

Examples of distinct axons in the PC layer in transverse 50-μm Cb sections labeled by transport from horseradish peroxidase injections. A: low-power micrograph counter-stained with cresyl violet shows an injection site into left vCb. B: labeled processes were traced using Neurolucida, revealing transverse-oriented axons in the PC layer extending far across the midline. C: high-power micrograph without counterstaining showing labeled transverse-oriented axons adjacent to PCs, 1-mm lateral to the midline, contralateral to injection site. Green arrowheads on each side mark the level of these labeled axons. In contrast to these large smooth axons, note the small beaded parallel fiber labeled in the ML above labeled with blue arrowheads. D: same region as C after cresyl-violet counterstaining shows that the large, smooth, transverse-oriented axons travel in the PC layer, while the parallel fiber is within the ML. E: terminal boutons (adjacent to red asterisks) are observed at even higher magnification near PCs more laterally in Cb (see box in inset). F: low-power image of injection site into rostral Cb, from which transverse-oriented labeled axons emanate, travel long distances in the PC layer. Boxed region is magnified below to show very lateral axons turning ventrally to enter the peduncle.