Fine structure and cytochemistry of the interaction between Fonsecaea pedrosoi and mouse resident macrophages

The interaction between conidia of Fonsecaea pedrosoi and mouse resident peritoneal macrophages was observed by light microscopy and by scanning (SEM) and transmission (TEM) electron microscopy. The conidia first attached to the surface of the macrophage and were then ingested. Prolonged incubation of the macrophage cultures showed proliferation of intracellular fungi as well as those which remained attached to the macrophage surface. The conidia were ingested by a typical phagocytic process, with formation of a phagosome. Macrophage lysosomes were observed to fuse with the phagosomes by immunofluorescence microscopy of macrophages previously labeled with acridine orange, by TEM of thin sections of macrophages labeled with albumin-gold, and by ultrastructural localization of acid phosphatase within the phagosomes.