In this study, we examine new cytochemical aspects of the fimbria-mediated adhesion of the oral facultative pathogen Candida albicans. A wild-type strain of the yeast was grown with and without sucrose supplementation for 8 days. Osmium tetroxide, uranyl acetate (UA), ruthenium red (RR), and cupromeronic blue (CB) staining with critical electrolytic concentrations (CECs) and tannic acid-metal salt technique (TAMST) were applied to specimens separately or in combination for transmission electron microscopy (TEM) examination. Cytochemically, two types of fimbriae of C. albicans were distinguished: RR-positive fimbriae of polyanionic glycoconjugates and CB-positive fimbriae with a ceasing point of 0.3 M MgCl2 where no staining of sulfated carboxyl-rich and/or phospho-glycoconjugates occurred. Additionally, CB-positive intercellular fibers were observed, which seemed to be involved in intercellular adhesion. The present protocol enables, for the first time, a partial cytochemical differentiation between at least two kinds of yeast fimbriae.
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