THE CHORIOALLANTOIC ARTERY BLOOD-FLOW OF THE CHICK-EMBRYO FROM STAGE-34 TO STAGE-43

Chorioallantoic artery blood flow and heart rate were studied in the c hick embryo from stage 34 until stage 43 (d 9-16 of 21-d incubation). Baseline blood flow profiles of the chorioallantoic artery were measur ed with a flow probe (Transonic) in 100 chick embryos. The eggs were o pened at the air cell and placed in a small plexiglass box with a cont inuous gas flow of a N-2/O-2 mixture (5 L/min), at 38 degrees C and 60 % humidity. The chorioallantoic artery was localized near the fetal ab domen and placed in the lumen of the Transonic flow probe. The heart r ate was derived from the blood flow signal. The mean chorioallantoic a rtery blood flow rose from 0.35 +/- 0.14 mL/min (mean +/- SD) at stage 34 to 3.13 +/- 1.49 mL/min at stage 43 (R(2) = 0.69, p < 0.0001), whi ch correlated with an increase in body weight (1.51 +/- 0.18 g to 15.0 8 +/- 0.76 g). Heart rate increased from 195 +/- 38 beats/min at stage 34 to 289 +/- 13 beats/min at stage 43 (R(2) = 0.38, p < 0.0001). The chorioallantoic artery blood flow, which in avian species correlates with umbilical blood how in mammals, increased with incubation time as reported in the mammalian fetus. This study shows that the chick embr yo could be useful as a preparation for further perinatal cardiovascul ar research.