Goldfish PKL and lamprey PTL were incubated with both zymosan and apoptotic cells (5∶1 ratio for each) for 2 h and 6 h, respectively. (A) To investigate the effects of pre-incubation with apoptotic cells, apoptotic cells were added 2 h prior to zymosan. Respiratory burst (measured as % DHR positive) was then analyzed based on phagocytic capacity across the four resulting sub-populations: non-phagocytic cells, phagocytes containing only zymosan, phagocytes containing only apoptotic cells, and phagocytes that contain both. (B) The percent of total population found in each of the four sub-populations of (A); no internalization, zymosan only, apoptotic cells only, zymosan and apoptotic cells. (C) The phagocytic index of the Zym+AC group in (A). For all n = 4, examined over a minimum of two independent experiments. * p<0.05 and ** p<0.01 compared to No;+p<0.05 and++p<0.01 compared to Zym.