Transmission electron microscopy images of monkey retina after subretinal injection of balanced salt solution.

Retinal structures of the control group (no injection of balanced salt solution; BSS) are well-preserved at 1 week (A) and 6 weeks (B) after injection. The minimum-pressure group (BSS injection at 6 psi) shows a shorter photoreceptor outer segment (OS) than the control group at 1 week after injection (C, bidirectional arrow). The OS is restored at 6 weeks after injection (D, bidirectional arrow). The retinal pigment epithelium (RPE) is well-preserved throughout the experimental period (C and D). Conversely, the high-pressure group (BSS injection at 20 psi) shows degeneration of the OS (bidirectional arrow in E) and migration of RPE cells (arrows in E), leading to multiple RPE layers at 1 week after injection. Regeneration of the OS (bidirectional arrow in F) and flattening of the RPE (arrows in F) were observed at 6 weeks after the injection. Scale bars = 10 μm.