Experimental study of the formation of the heart tube in the chick embryo.

A study was made of the development of the heart tube beginning from Hamburger & Hamilton (1951) stage 8+ up to stage 12. We used labelling with particles of iron oxide followed with time-lapse cinemicrophotography, staining with methylene blue, serial section and cutting the embryo in two halves. Our results led to the conclusion that the tubular heart is formed by the addition of precardiac material into its posterior end, but in addition it is necessary to consider the fusion of the myocardium in a cephalic direction, starting with the fusion of both heart primordia at the rostral end. By this fusion the most anterior part of the heart up to stage 12 is formed.