Fig. 4. Cardiac and lymph gland defects in Hand mutant embryos. (A-I) Stage 16 embryos labeled with cardiac and lymph gland markers. About 20% of the Hand mutant embryos showed a range of cardiac morphological defects (D-F), including misalignment of Mef2-expressing cardioblasts, reduced Odd-expressing pericardial cells and lymph gland progenitors. Embryos with more severe defects (about 3%) showed a significant reduction of all three cell types (G-I). The ring gland, which is adjacent to the lymph gland anteriorly and is labeled by Pericardin, is not affected (E,F), nor are somatic muscles, labeled by Mef2 (D,F). Arrowheads indicate the positions of the lymph gland.