O2 tension in the spinal cord of the avian embryo

Abstract

A small recessed-tip O2 microelectrode was used to construct frequency distributions of PO2 in the chicken embryonic spinal cord during the last week of development (15–20 days). PO2 was remarkably low and stable at a given spinal locus. Electrode movement led to little change in the absolute level of tissue PO2 for a given day in the development. Spontaneous fluctuations occurred, predominantly in the motor columns, whose frequencies were dependent on the stage of incubation. PO2 decreased progressively; the most significant decline occurred between 16 and 17 days in ovo [19.2 +/- 1.7 (SD) to 11.5 +/- 2.7 Torr, respectively]. This decline in tissue PO2 at 16 days precedes dramatic alterations in spinal cord electrical activity and the resulting embryonic behavior.