[Influence of extrinsic factors on the development of the bulboventricular loop of the chick embryo].

Of several chick culture methods investigated, New's technique produced the greatest percentage of normal bulboventricular loops. In embryos with two left cardiogenic areas or with two right cardiogenic areas or with the areas exchanged, the bulboventricular loop develops to the right in the cases in which there is integration. When each of the areas was permitted to be expressed without the other and there was closure of the gut, both areas were expressed according to their intrinsic quality. We believe that in stage 5, the type of loop is not determined.