Scanning-beam electron microscopy of the conidia of the brown and albino filamentous varieties of Histoplasma capsulatum.

Abstract

Aspects of the surface appearance and external morphology of the conidial forms of the albino and brown filamentous varieties ofHistoplasma capsulatum as seen by scanning-beam electron microscopy are described and illustrated by electron micrographs. Septal areas between the hyphal cells of the supporting mycelium are seen as slightly elevated annular rings or ridges. The smooth micro- and macroconidia of the albino filamentous variety show a fine wrinkling and delicate irregularities of surface texture. Macroconidia of the brown filamentous variety are illustrated showing variations in numbers and respective length of the conspicuous wall projections or tubercles. The 3-dimensional perspective, unusual depth of focus, and high resolving power of the stereoscan technique permitted observations of external conidia morphology unattainable by other methods of study.