17 October 1997
Vol 278, Issue 5337

About The Cover

Scanning electron micrograph of the nematode Pristionchus pacificus (~1 millimeter long). Ventral epidermal cells differ in fate among nematode species. In Caenorhabditis elegans, these cells fuse with the epidermis, whereas in P. pacificus, the homologous cells die of apoptosis. Genetic analysis in Pristionchus indicates that this evolutionary alteration is driven by different intrinsic properties of the epidermal cells. See 452. [Image: J. Berger, A. Eizinger, R. J. Sommer]