Self-differentiation of the heart rudiment of the newt (Cynops pyrrhogaster).

In a previous study, the cultured heart rudiment of the Japanese newt embryo of stage 15 (early neurula) could be differentiated into beating myocardial cells in a ROSE's chamber filled with BARTH and BARTH's inorganic solution with the addition of 10% calf-serum. With the use of the inorganic solution free of serum, however, even the material after stage 22 (early tail-bud) could not be differentiated. In the present work, culture of the heart rudiment of the embryo from stage 16 to 22 was performed in fine glass capillary tubes filled with a BARTH and BARTH's salt solution free of calf-serum. At stages 21 and 22 the heart rudiment differentiated successfully into beating myocardial cells. It was thus known that the heart rudiment at stage 21 already attains its self-differentiating potentiality, because there was obviously no effect of other cellular substances in this case. In the culture performed in the glass capillary, diffusion of the metabolites of the cultured cells was limited since the culture medium was very small in quantity. Therefore, differentiation is believed to have been brought about by the medium thus conditioned in the capillary.