[Tail gut regression and associated phenomena in chick embryo (author's transl)]

The regression of the tail gut and the associated phenomena in chick embryo were studied using cytological and biochemical methods. The cells of the tail gut begin degenerating at stage 20. The regression is completed at stage 24. The remnant of the primitive streak which have been incorporated into the tail bud degenerate at the same time. During this period dead cells are sporadically found in the other tissues of the tail bud, chiefly in the mesenchym. The morphological characteristics of cell degeneration and elimination, in the tail gut as in the mesenchyme, are defined. The biochemical study showed that the degenerative phenomena correspond to an enhanced activity of acid phosphatase. This study shows further that these phenomena do not change the total growth rate of the tail bud while they are developing.