Scanning Electron Microscopy


Cells from Xenopus laevis blastulae have a poorly developed ability to adhere to Sepharose beads covalently coupled to bovine plasma fibronectin (FN-beads). They do, however, have the ability to adhere to con A-beads and cytodex-1 and cytodex-3 beads. Beginning at the early gastrula stage, there is a progressively increasing ability of cells to adhere to FN-beads. Gastrula cells adhere to FN-beads by the formation of large ruffling lamellipodia. These cells can translocate on the surface of FN-beads; and when attached to both beads and the surrounding glass substratum of culture vessels, have the ability to move the beads extensively. Gastrula cells also have the ability to adhere to but not move upon con A-beads, wheat germ agglutinin-beads, and soy bean agglutinin-beads. They do not adhere significantly to Tetragonolobus purpureas agglutinin-beads. These results suggest that there are increasing numbers of fibronectin receptors present on the surface of embryonic amphibian cells during the period of gastrulation. They may explain the differential distribution of fibronectin-containing fibrils in vivo as observed by scanning electron microscopy.

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