Blood oxygen consumption and erythrocyte types in embryonic and postnatal chicken

Abstract

In an extension of previous work showing that oxygen consumption (MO2) of chick blood cells declines from 5 to 14-15 days incubation age, declines more steeply to hatching, rises abruptly up to 4-6 posthatch days, and declines thereafter, we investigated the succession of embryonic and posthatch erythrocytic types by performing differential erythrocyte (RBC) counts. MO2 of RBC groups separated by density gradients and fractionation into younger and older RBC populations were measured in 1- to 22-day-old posthatch chicks. The embryonic MO2 decline can be attributed to the appearance of erythrocytic types with successively lower metabolism. The MO2 slope change at 14-15 days incubation coincides with the predominance of definitive erythrocytes with oval nuclei over other cell types. The posthatch MO2 rise is due to a temporary invasion of immature RBC, especially postnatal polychromatic erythroblasts. MO2 then decreases as these cells mature.