Heart Rate of the Developing Chick Embryo.

Abstract

The heart rate of chick embryos was measured daily by ballistocardiography. This new technique afforded ideal conditions for observing embryonic heart beats with minimum disturbance to the embryos. The heart rate increased from day 4 through day 10 and then decreased slightly until hatching time. The average frequency at 10 days was 280 bpm and 263 bpm at 19 days of incubation. No significant difference was observed in the average daily heart rate of embryos from 4 different genotypes. Mechanical disturbances or alterations in temperature had a marked effect on the heart rate of the embryo. Brief exposure to room temperature or slight injuries, such as those following insertion of electrodes, resulted in a decreased heart rate.