Chorioallantoic artery blood flow in avian species correlates with umbilical blood flow in mammals. Chorioallantoic artery blood flow and heart rate were studied in the 100 chick embryos from stage 34 until stage 43 with extends from days 9 to day 16 of a 21-day incubation period.
Eggs were opened at the air cell and placed in a small temperature and humidity controlled plexiglass box with a continuous gas flow of a N2/O2 mixture (5 L/min). The chorioallantoic artery was identified near the fetal abdomen and a 0.5 mm Transonic V Flowprobe was applied to the artery to measure flow. The heart rate was derived from the blood flow signal.
Mean blood flow rose from 0.35 mL/min at stage 34 to 3.13 mL/min at stage 43 which correlated with an increase in body weight from 1.51 to 15 grams during the same period. Heart rate increased from 195 to 289 beats/min during the same time period. The study lead to a follow-up study that examined the effect of hypoxia on chorioallantoic blood flow and heart rate in 140 chick embryos. Flowprobes were used to measure peak flow and blood flow acceleration in addition to measuring chorioallantois arterial flow and heart rate.