In the early stage, A. fumigatus germination was delayed after cyclophosphamide treatment. (A): At a low magnification, no significant histological lesion was observed. B: Only small clusters of conidia were multifocally detected (arrowheads). C. At a high magnification, only small infiltrates of neutrophils were noted in bronchiolar and alveolar spaces. (D): Non-germinated and early germinating conidia were observed in these inflammatory infiltrates. (E): Intra-alveolar conidia at a very early stage of germination (swollen conidia). Some conidia were observed in the cytoplasm of alveolar macrophages (arrowhead). (F): Intra-bronchiolar conidia were either swollen or started to form hyphae. Note that this stage of maturation is much less pronounced than observed in the early stage of cortisone acetate (Figure 6D) and RB6-8C5 treatment (Figure 9D). A, C: HE staining; B, D, E, F: GMS staining.