Dorsal aortic flow velocity in chick embryos of stage 16 to 28

The objective of this study was to evaluate two Doppler frequency-detection methods to measure blood flow velocity in the developing chick embryo. We compared the commonly used directional zero-crossing counter and a customiz ed digital bidirectional spectrum analyzer. At development stages 16 up to 28 (2.5 to 6 days incubation), a reversed How component in the dorsal aorta was demonstrated using the bidirectional spectrum analyzer. Dorsal aortic velocities obtained with the directional zero-crossing counter were signifi cantly lower than with the bidirectional spectrum analyzer in stages 16, 20 and 28. In addition to the differences in the absolute velocity values, th ere was also a remarkable discrepancy in the velocity waveform shape using the two Doppler frequency processors. The calculated heart rate using the t wo Doppler frequency processors was identical. It is concluded that a Doppl er velocity detector based on spectral analysis is superior to the hitherto used zero-crossing counter in the chick embryo. With the customized digita l bidirectional spectrum analyzer, we can accurately measure the hemodynami cs of the developing chick embryo.