Some aspects of regeneration in the scyphistoma of Cassiopea (class scyphozoa) as revealed by the use of antimetabolites and microspectrophotometry

Abstract

As a continuation of studies of the regenerative capacities of the scyphistoma of Cassiopea, a series of experiments was undertaken in which (i) regenerating fragments were cultured in the presence of various antimetabolites and (ii) Feulgenstained nuclei from control animals and regenerating fragments were measured by scanning, integrating microspectrophotometry. The results of the antimetabolite experiments were complex and variable but nonetheless suggested that normal regeneration of functional heads from fragments requires the synthesis of DNA, RNA, and protein. Regardless of the type of antimetabolite, the most frequently observed morphological effect was prolonged or arrested development. None of the antimetabolites produced characteristic or unique abnormalities, although variation was observed in the ability of the inhibited fragments to recover from the various antimetabolites. Microspectrophotometric measurements of Feulgen-stained nuclei from control animals revealed that approximately 25% of the nuclei contained more than the diploid amount of DNA and thus were in either the S or G2 phases of the cell cycle. In regenerating fragments, the frequency of nuclei in this category dropped progressively to less than 6% by the end of 3 days but returned nearly to control levels by the end of six days. The nuclei also became somewhat enlarged and less dense during regeneration. Copyright © 1974 by the American Society of Zoologists.