Figure 2. Sema5A and Sema5B Cooperate During Retinal Development to Constrain Neurite Extension from Multiple Amacrine and RGC Subtypes Within the IPL in vivo.
(A–H) Wild-type (A, C, E and G) and Sema5A−/−; Sema5B−/− (B, D, F and H) adult retina sections were immunostained with antibodies against Dab-1 (A and B), ChAT (C and D), calretinin (E and F), and calbindin (G and H). Subtypes of amacrine cells and RGCs labeled by these markers exhibit characteristic neurite arborization within the IPL of wild-type retinas (A, C, E and G). However, all of these neuronal subtypes extend aberrant neurites (yellow arrows) toward the INL, and sometimes into the OPL, in Sema5A−/−; Sema5B−/− retinas (B, D, F and H).
(I–N) Wild-type (I, K and M) and Sema5A−/−; Sema5B−/− (J, L and N) postnatal retina sections from P2 (I and J), P4 (K and L), and P7 (M and N) mice were immunostained with anti-calbindin. At P2, neurite outgrowth from calbindin-positive cells does not apparently differ between wild-type and Sema5A−/−; Sema5B−/− retinas (I and J), however, at P4, calbindin-positive cells extend aberrant neurites toward the INL in Sema5A−/−; Sema5B−/− retinas (yellow arrows, L). At P7, ectopic stratification of aberrant neurites from calbindin-positive cells is prominent within the INL of Sema5A−/−; Sema5B−/− retinas (yellow arrow, N).
(O and P) Wild-type (O) and Sema5A−/−; Sema5B−/− (P) P7 retina were immunostained with anti-Pax6. In Sema5A−/−; Sema5B−/− retinas, misdirected neuronal processes, including calbindin-positive cell neurites, split Pax6-labeled cells into two layers in the inner region of the INL (yellow arrow, P).
Scale bars: 50 μm in H for A–H, and in P for I–P.