Fig. 4. Activation and inhibition of BMP cause distinct hematopoietic defects. (A) Wright-giemsa-stained blood collected from control tadpoles or from tadpoles in which BMP signaling had been misregulated. Black arrows indicate RBCs; white arrows indicate WBCs. (B) The mean number (± s.e.m.) of WBCs (white bars), RBCs (black bars) and total blood cells (shaded bars) present in three random fields of blood from at least 30 control or experimental embryos is shown. (C) Ratio of WBCs to RBCs, calculated from data shown in B. (D) TUNEL analysis of apoptotic cells (arrows). Nuclei were stained with propidium iodide. (E) Percentage apoptotic cells (mean ± s.e.m.) determined by counting total and TUNEL-positive cells in three random fields of blood from at least 24 embryos.