Schistosoma mansoni: evaluation of selected preparative procedures for transmission and scanning electron microscopy.

Evaluation of numerous procedures for collection and preparation of Schistosoma mansoni for scanning (SEM) and transmission microscopy (TEM) revealed that some commonly used methods result in introduction of osmotic or mechanical damage. Modification and selection of appropriate procedures allowed elimination of these artifacts. Not eliminated by these procedures, however, were several kinds of spheres and blebs that were either external to the apical plasma membrane of the tegument or budding from it. After careful examination of all procedures, we concluded that these spheres appear to some extent on all schistosomes prepared for either SEM or TEM and may represent either a normal component of the schistosome surface, a constant host contaminant, or an artifact not eliminated by any of the multiple modifications of technique examined.