Figure 4. Number of regulated genes, total, upregulated, and downregulated, is shown by Gene Ontology at 3, 7 and 14 days. The total number (A) of apoptosis-related genes is maximal at 14 days for all subgrouping except for ‘negative regulation of programmed cell death’ which peaks at 7 days. The number of upregulated (B) and downregulated (C) genes increases over the 14 day treatment period in each ontology category except in (B) where ‘negative regulation of programmed cell death’ is maximal at 7 days. This indicates a loss in potential protective mechanisms against apoptosis in the hyperoxic mouse retina.