Thymocytes from larval 8-day-old rag2-EGFP-bcl-2 transgenic fish are resistant to irradiation- and dexamethasone-induced apoptosis. Fluorescent microscopic analysis of 8-day-old rag2-GFP transgenic fish without treatment (A), 2 days after irradiation (15 Gy; B), or 3 days after dexamethasone treatment (250 μg/mL; C). Eight-day-old rag2-EGFP-bcl-2 transgenic fish without treatment (D), 2 days after irradiation (E), or 3 days after dexamethasone treatment (F). Location of the thymus is denoted by arrows and labeled (T). Asterisk denotes autofluorescence of the swim bladder. Fish oriented with anterior to the left and dorsal to the top.