RESUMEN
The ultrastructure of asexual spores (conidia) produced by the mycelial form of Paracoccidioides brasiliensis was studied for the first time with transmission electron microscopy, using thin sections of aldehyde-osmium-fixed and epoxy-resin-embedded samples. The various types of conidia observed in the sections correlated well with previous light-microscopic descriptions. These types were intercalary or apical conidia, depending on their location along the originating hyphae. As in previous studies they were characterized as arthroconidia, aleuriospores and sessile or pedunculate pyriform conidia. The sporogenous cells were clearly distinguished from hyphal cells by the thickness and appearance of their cell walls. Copious fibrillar material (glycocalyx) detected at the cell surface was stained with ruthenium red during the fixation process. Typical subcellular organelles (nucleus, nucleolus, mitochondria, ribosomes, etc) were found in most of the sections. It was concluded that the spores produced by the mycelial phase of P. brasiliensis possess all attributes of viable and physiologically competent eukaryotic cells.
Asunto(s)
Paracoccidioides/ultraestructura , Humanos , Microscopía Electrónica , Paracoccidioides/fisiología , Esporas Fúngicas/ultraestructuraRESUMEN
The conidia produced by the mycelial form of Paracoccidioides brasiliensis were examined by scanning electron microscopy for the first time. Several different conidial types were characterized. These included intercalary arthroconidia, several types of septate conidia that are formed from other conidia, pedunculate conidia, and terminal hyphal conidia. In addition, the ultrastructure of the supporting pedestal of the pedunculate conidium was found to be separated from the mother conidium by a septum in some instances, and at other times it was not.