Hemodynamics of the stage 12 to stage 29 chick embryo. Circ Res 65: 1665–1670

The heart is the first functioning organ in the embryo and provides blood flow during cardiac morphogenesis from a muscle-wrapped tube a few cells thick to the four-chambered pump. We described the hemodynamics of the chick embryo from stage 12 (50 hours of a 21-day incubation) to stage 29 (6 days), during which the embryo weight increased 120-fold. We measured ventricular, embryo and extraembryonic vascular bed wet weights, dorsal aortic blood flow with a directional pulsed-Doppler velocity meter, and ventricular and vitelline arterial blood pressures witfa a servo-null micropressure system. The data are reported as mean±SEM. With rapid development and morphogenesis, dorsal aortic blood flow increased from 0.015 ±0.004 to 2.40 ±0.20 mm3/sec parallel to the geometric increase of wet embryo weight from 2.22±0.10 to 267.5±9.7 mg. Dorsal aortic blood flow normalized for embryo and extraembryonic weight remained relatively constant (Y=2.13+0.02X, r=0.23, SEE=0.03). Stroke volume increased from 0.01 ±0.003 to 0.69 ±0.03 mm3, and heart rate doubled from 103±2 to 208±5 beats/min. Systolic, diastolic, and mean vitelline arterial pressure increased linearly from 0~32±0.01, 0.23±0.01, and 0.28±0.01 mm Hg at stage 12 to 2.00±0.06, 1.22±0.03, and 1.51 ±0.04 mm Hg, respectively, at stage 29. Ventricular peak systolic an