Cells from Rana pipiens gastrulae and arrested hybrid gastrulae show differences in adhesion to fibronectin-Sepharose beads

Experiments were performed to examine adhesion of Rana pipiens gastrula cells and arrested hybrid gastrula cells to fibronectin‐Sepharose beads (FN‐beads). Blastula cells from both normal and hybrid embryos show poor adhesion to FN‐beads. Beginning at the early gastrula stage, however, normal cells show a progressively increasing tendency to adhere to beads. In two different arrested hybrid embryos, cells from all developmental stages lack the ability to adhere to beads. A third hybrid shows an increase and then a decrease in cell‐bead adhesion. A fourth hybrid shows a late increase in cell‐bead adhesion in animal‐half cells and no increase at all in vegetal‐half cells. Blastula‐stage cells have the ability to adhere to con A–beads and two kinds of Cytodex beads but will not adhere to FN‐beads. Similarly, some cells from arrested hybrid embryos lack the ability to adhere to FN‐beads but will adhere to con A–beads and cytodex beads. Observations in the light and scanning electron microscope show that normal cells form lamellipodia on FN‐beads and move about actively on them, much like they do in vivo on surfaces coated by fibrils containing fibronectin. For adherent hybrid cells attached to beads, one kind does so by small pseudopodia but does not move on them and another kind forms active lamellipodia at the tips of fusiform cells and moves on beads.