Figure 4.

Internucleosomal DNA fragmentation is attenuated by cortisol. E15 eggs were injected with cortisol (1 mg per egg; lane 4) or carrier (lane 3) and incubated for an additional 48 h before the retina was excised. Retinal explants were cut into pieces and organ-cultured for 24 h. DNA was extracted, and samples from an equal numbers of cells (5 × 10⁷ cells per lane) were analyzed by gel electrophorsis and visualized with the fluorescent intercalating dye ethidium bromide. DNA was extracted from untreated E17 retina immediately after tissue excision (lane 2). Molecular weight markers are from a HaeIII digest of ØX174 phage DNA (lane 1).