A comparative study of the effects of egg rotation (gravity orientation) and UV irradiation on anuran vs. urodele amphibian eggs.

The response of various anuran and urodele eggs to a brief rotation prior to first cleavage were observed. In all instances, the dorsal lip formed on the side of the egg which opposed gravity during the rotation. The ability of egg rotation to prevent the series of developmental abnormalities associated with UV irradiation of the uncleaved egg was also examined. Anuran and urodele eggs responded to those manipulations in a similar fashion. These results should facilitate future studies on the mechanisms involved in the establishment of the dorsal/ventral polarity of the amphibian egg.