βH1-globin, but not εy-globin, transcripts are present in the early fetal liver. Neighboring sections of E12.5 liver were hybridized to radioactive probes (exposed grains indicating hybridized probe are colorized red). β1-globin is expressed predominantly in liver (fl) cells, while εy-globin is expressed in circulating primitive erythroid cells (fb). βH1-globin is expressed in low levels in primitive erythroid cells as expected, but also more highly expressed in a subset of cells in the liver. Size bar equals 100 μm. Images were processed as described in “In situ hybridization.”