The video sequence below is a computer- generated morph of still photos from an original journal article by Wilson and Keller (19??) in which the behavior of open-face sandwiches was extensively documented. The deep cells of the DIMZ undergo massive convergence and extension. The convergence and extension occurs in two majort steps. First, radial intercalation (i.e., through the thickness of the explant) occurs to flatten the explant with comparatively little extension and narrowing. Next, mediolateral interdigitation narrows and elongates the explant dramatically. In contrast to the original sandwich explants, in which two identical strips of tissue are fused together with their deep cells touching one another in the middle of the explant, the cells of the DNIMZ undergo relatively little convergence and extension in open-faced explants.
A morph sequence depicting convergence and extension in the dorsal involuting marginal zone of Xenopus explanted in vitro.