Figure 4. In situ hybridization for Eph-A6 expression in a Fd 115 macaque retina. A: At the developing fovea and in adjacent temporal retina, peak Eph-A6 mRNA expression is detected in the inner ganglion cell layer (GCL) within the foveal avascular area (bracket). Large arrows mark vessels at the inner margin of the perifoveal plexus. The area between the two large arrows is devoid of vessels. Smaller arrows indicate vessel profiles deep in the GCL (GCL plexus), which is a characteristic of macular vessels. B: Approximately 500 µm further into temporal retina, vessels (arrows) are present in the inner and outer GCL, and levels of Eph-A6 mRNA in the GCL are lower, and more uniform across the depth of the GCL, compared with A. Together, the images show two gradients of Eph-A6 expression: a high-to-low gradient from inner to outer GCL at the developing fovea (in A), and a high-to-low gradient from fovea to periphery (top left GCL in A to lower right GCL in B). Both A and B are at the same magnification. Abbreviations: inner nuclear layer (INL); outer nuclear layer (ONL).