ROLE OF CELL DIVISION IN XENOPUS LAEVIS SKIN GLAND DEVELOPMENT

Approximately 3.5 days before rudiments with ca. 5 or more cells (recognizable rudiments) appear in Xenopus forelimb skin during metamorphosis, there is an increase in the frequency of mitosis in the epidermis of this skin. Subsequent to this increase in mitosis, but prior to the appearance of recognizable rudiments, doublets of contiguous mitotic cells can be found in this epidermis. These doublets persist throughout the stages of metamorphosis when rudiments are being initiated, and diminish when rudiment formation is reduced. Inhibition of mitosis by fluorouridine-5′-deoxyribose or colchicine prevents the formation of new gland rudiments with ca. 5 or more cells in them. Our previously estimated duration of the gland cell division cycle of ca. 40 hours permits a sufficient number of divisions to occur to form clones of cells recognizable as gland rudiments in the time available for this. These data are consistent with a clonal origin of early Xenopus multicellular skin gland rudiments, and they are difficult to reconcile with a mechanism of rudiment formation that involves only cell aggregation. © 1969.