Spontaneous apoptosis in VEGF-treated thymocytes. (A) Spontaneous apoptosis of thymocytes cultured ± VEGF (100 ng/mL) in vitro for 3, 6, or 24 hours. Results are presented as the mean percentage of early-apoptotic thymocytes (Annexin V⁺, PI^–) (n = 9). (B) Annexin V staining of thymocytes from mice treated in vivo ± VEGF for 14, 21, and 28 days. Mice treated with VEGF as described in Figure 1 were killed and thymocytes analyzed for early-apoptotic cells via Annexin V staining (PI^–) (mean ± SE; N > 3). Control shown in panel B is an average of controls from 0-, 14-, 21-, and 28-day samples. *Denotes statistical significance.