Figure 5.

Laminar-specific differences in retinal terminal morphology in ventral lateral geniculate nucleus (vLGN). A-C. Retinal projections in P35 wild-type mice were labeled by intraocular injection of fluorescently conjugated cholera toxin subunit B (CTB). Left eyes were injected with Alexa Fluor 555 CTB (magenta) and right eyes were injected with Alexa Fluor 488 CTB (green). ‘Contra’ denotes projections originating from the contralateral retina and ‘ipsi’ denotes projections originating from the ipsilateral retina. Three sections of lateral geniculate nucleus (LGN) from different rostral to caudal regions of the right hemispheres are shown. In more caudal sections, a small, lateral region of vLGN emerges that contains retinal terminals that appear to share characteristics of dorsal lateral geniculate nucleus (dLGN) retinal terminal morphology (arrows). Insets in B,C show high magnification images of this regions, which we term the lateral shell of caudal vLGN (lcvLGN). ‘Contra’ denotes projections originating from the contralateral retina and ‘ipsi’ denotes projections originating from the ipsilateral retina. Outlines of dLGN and the external division of vLGN are depicted with white dots. d, dLGN; v_e, external division of vLGN; v_i, internal division of vLGN; i, IGL. D-G. High magnification images of CTB-labeled retinal terminals in dLGN (D), external division of the vLGN (E), IGL (F), and lcvLGN (G). All images are maximum projection confocal images. H. Relative CTB-labeled retinal terminal areas (compared to retinal terminals in dLGN) were quantified in single optical sections of dLGN, vLGN, IGL and lcvLGN. Retinal terminal sizes in IGL, vLGN and lcvLGN were statistical smaller than those in dLGN (P <0.0001 by Neuman-Keuls Test). CTB-labeled terminal sizes in IGL and vLGN were also significantly smaller than those in lcvLGN (P <0.02 by Neuman-Keuls Test), but were not statistically different from each other (P = 0.48). Scale bar in A = 200 μm for A-C and in G = 25 μm for D-G.