Figure 3.

Remodeling of host rd¹ retina and formation of putative synaptic-like connections

(A) Large numbers of GFP⁺ WT cones in close proximity to the host inner retina. Host rd1/FoxN1^nu (rd¹) PKC-α⁺ rod bipolar cells (BCs) extended processes into the cell mass (ROI1, ROI2, arrowheads). Post-synaptic protein, mGluR6, was seen within those processes (ROI1, ROI2, arrows).

(B) BCs do not extend dendrites beyond the inner retina, and mGluR6 is not expressed in untreated eyes.

(C) Vesicular glutamate transporter 1 (VGLUT1) was seen in the cell mass in close proximity to host rd¹ BC dendrites (ROI1–3).

(D) Pre-synaptic protein Synaptophysin was present in the host IPL and in transplanted GFP⁺ cones.

(E and F) In areas of high donor cell density, numerous putative RIBEYE/mGluR6 complexes were seen in close proximity to one another (ROIs). Images are representative of n = 10 WT and n = 8 CNGB3-transplanted eyes.

(G) TEM image showing presence of ribbon synapses (arrows), including multiple ribbons within a single terminal (left), within the area of injection.

Scale bars, 25 μm (A–C and E); 12.5 μm (ROI2 in A and F); 3 μm (ROI1 in A, ROI3 in C and F); 500 nm (G).