The nature of immature avian erythrocytes in severe anaemia induced by phenylhydrazine.

Hens were rendered severely anaemic by the use of phenylhydrazine and the characteristics of the polychromatic erythrocytes appearing in the blood examined. Even the least-dense polychromatic erythrocytes obtained after density fractionation of anaemic blood on BSA density gradients had a volume mode only 1-5 times that of mature erythrocytes. Also the immature cells always contained less haemoglobin than mature erythrocytes. It was concluded that in severe anaemia avian erythropoiesis still consists of only one cell line, and that cells do not miss divisions as is believed to be the case in mammalian erythropoiesis.