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Blood oxygen consumption and erythrocyte types in embryonic and postnatal chicken
Insights
Chick blood cell oxygen consumption (MO2) changes are linked to erythrocyte (RBC) types. Embryonic MO2 declines with RBC maturation, while a posthatch rise is due to immature RBC invasion before they mature.
Area of Science:
- Physiology
- Cell Biology
- Developmental Biology
Background:
- Previous studies documented oxygen consumption (MO2) changes in chick blood cells during embryonic development and early posthatch life.
- The precise cellular mechanisms driving these MO2 fluctuations, particularly the role of different erythrocyte populations, remained unclear.
Purpose of the Study:
- To investigate the succession of embryonic and posthatch erythrocytic types.
- To correlate changes in erythrocyte populations with measured oxygen consumption (MO2) in chick blood cells.
Main Methods:
- Differential erythrocyte (RBC) counts were performed to identify and quantify different cell types.
- Oxygen consumption (MO2) was measured in separated younger and older RBC populations using density gradients and fractionation.
- Measurements were conducted on blood cells from chicks aged 1 to 22 days posthatch.
Main Results:
- The decline in embryonic MO2 is associated with the emergence of erythrocytic types exhibiting lower metabolic rates.
- A significant shift in the MO2 slope around 14-15 days of incubation correlates with the dominance of definitive erythrocytes.
- The abrupt rise in posthatch MO2 is attributed to a temporary influx of immature erythrocytes, specifically polychromatic erythroblasts, followed by a decrease as these cells mature.
Conclusions:
- The observed patterns of oxygen consumption (MO2) in chick blood cells are directly influenced by the developmental stage and type of erythrocytes present.
- The transition from embryonic to posthatch erythropoiesis involves distinct cellular changes that modulate overall metabolic activity.
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.