Microscopic Observations on the Filopodia of Entamoeba histolytica*
This investigation was supported by the Medical Research Service of the Veterans Administration; Research Grant #AI-12649 from the National Institute of Allergy and Infectious Diseases. U.S. Public Health Service: the John A. Hartford Foundation, Inc., New York, New York; and a grant from the Division of Research Resources, National Institutes of Health, U.S. Public Health Service, for the use of the high voltage electron microscope at the University of Colorado, Boulder.
SYNOPSIS
Living Entamoeba histolytica trophozoites were examined by phase-contrast microscopy. Intact critical point dried trophozoites were examined by transmission electron microscopy at an accelerating voltage of 1000 kV (HVEM) and by scanning electron microscopy (SEM). Half and quarter m̈ thick sections of epoxy-embedded trophozoites were examined by HVEM. Many of the trophozoites of 2 strains examined had surface filopodia, 1 to over 100 pan in length. The cytoplasm of filopodia was continuous with the cytoplasm and bounded by surface plasmalemma bearing a glycocalyx. Structures called “surface-active lysosomes with trigger,”“dendritic plasmalemmal extensions,” and “extra-amebic vesicles” by previous investigators probably represent portions of filopodia demonstrated in the present study. Filopodia appear to be of frequent normal occurrence in E. histolytica and may function in: (a) endocytosis or pinocytosis; (b) exocytosis; (c) attachment to substratum; (d) penetration of tissue; (e) release of cytotoxic substances; or (f) contact cytolysis of host cells.
