Figure 3.

Retinal histology and TEM of Rp2^null retina. (A) Histologic analysis of paraffin sections of Rp2^flox (control) or Rp2^null mouse retina was performed at indicated ages. RPE, retinal pigment epithelium; OS, outer segment; IS, inner segment; ONL, outer nuclear layer; OPL, outer plexiform layer; INL, inner nuclear layer; IPL, inner plexiform layer; GCL, ganglion cell layer. (B) Morphometric analysis of ONL thickness of 1, 5, and 9 months Rp2^flox and Rp2^null retinas (n = 5). The ONL thickness was measured in μm along the vertical meridian at each defined distance from the optic nerve head. Data represent mean ± SEM. *P < 0.01. (C) TEM analysis of control (Rp2^flox, top) and mutant (Rp2^null, bottom) photoreceptors at 10 months of age show disorganized OS in the mutant retina. Insets (c, f) show cross-sectional view of the connecting cilium (CC) with 9 + 0 array of microtubules in both control and mutant mice. Arrows in (e) indicate degenerated OS discs in the mutant retina; arrowheads in (c, f) show normal morphology of the CC. Scale: (a, d) 5.0 μm; (b, c, f) 0.5 μm; (e): 1 μm.