Figure 2. Apoptotic photoreceptor nuclei during retinal degeneration in tubby mice

TUNEL-labeled longitudinal sections through retinas of an adult wild type mouse (A) and tubby mice at the age of PN 14 (B), PN 16 (C), PN 19 (D), PN 21 (E), and PN 23 (F). The number of TUNEL-positive apoptotic photoreceptor cells in the outer nuclear layer (ONL) gradually increased from PN 14 to the peak at PN 19, followed by a decrease to a basic level at PN 23. Note: While a few TUNEL-positive nuclei were found in the inner nuclear layer (INL) in the PN 14 tubby retina, apoptotic cells are absent in older tubby mice in the inner retina. Scale bar represents 15 μm.