Figure 1.

Representative images of EPO immunostaining in C4 phrenic motor neurons. A, DAB staining revealed EPO expression in large, putative phrenic motor neurons (black box) and possible interneurons. B, Higher magnification of black box from A. C, CtB was intrapleurally injected to localize phrenic motor neurons (green cells in ventral horn). Scale bar (in C), 400 μm. D–F, EPO (E) is expressed in CtB-labeled phrenic motor neurons (see merged image, D) and surrounding neuropil. Scale bar (in F), 50 μm.