Scanning Electron Microscope Observations of Amoeba proteus During Phagocytosis*

Abstract

Phagocytozing A. proteus at different stages of forming foodcups were observed by scanning electron microscopy. A nonphagocytozing amoeba is characterized by dorsal and lateral ridges running longitudinally over the posterior half of the cell and its attachment to the substrate over small areas. When stimulated by prey organisms [Tetrahymena], the amoeba loses polarity and ridges and adheres to the substrate more firmly over a wider area of contact. Then it forms broad pseudopods to surround its prey and this results in the formation of foodcups. The surface of all amoebae is covered with small projections, and membranous blebs are often seen on the surface of phagocytozing organisms.