Fig. 6.

Light micrographs of 40-μm-thick cryostat coronal sections illustrating regenerated retinal fibers in the pretectum 46 weeks after grafting a segment of peripheral nerve between the left retina and the dorsal aspect of the left midbrain between the OPN and NOT and 5 d after intraocular injection of CTB.A, CTB-labeled retinal axons innervate the OPN extensively (toward the top left) and the rostral limit of the NOT (toward the middle and right). Scale bar, 35 μm. B, Extensive innervation of the NOT area with numerous varicosities resembling bouton-like endings in a more caudal section. Scale bar, 28 μm. Insets inA and B are drawings of the respective section of the midbrain, and the boxes indicate the region photographed. Scale bar, 1 mm.