Ruffling and locomotion in Rana pipiens gastrula cells

Abstract

Embryonic amphibian cells move during gastrulation, even though they are in contact with many neighboring cells. The behavior of these cells in vitro with respect to cell movement and contact inhibition is thus of interest. Cultures of isolated presumptive mesodermal cells of early Rana pipiens gastrulae were sealed with a coverslip and filmed under phase contrast at 16 frames/min. At the end of 30 min in vitro, cells settle to the substratum and form fan-like lamellipodia which are sites of cell attachment. Ruffling is qualitatively similar to that seen in many chick and mammalian cell types in vitro. Ruffles lift up and move back from marginal extensions of cells. When lamellipodia are symmetrically arranged around the cell periphery, no net translocation of the cell occurs. In contrast, when cells have a dominant lamellipodium (larger and/or more active), movement occurs in that direction. Cells may exhibit complex margins composed of microspikes, ruffles, and hyaline extensions of the cell draped between microspikes. When cells come in contact there is a local paralysis of ruffling. When cells lose contact, a broad ruffling lamellipodium often appears immediately at the former sites of contact.