Ultrastructure of the pseudo-cleistothecia produced by the Trichophyton mentagrophytes complex

The internal structure and the formation processes of pseudo-cleistothecia in Arthroderma vanbreuseghemii, a member of the Trichophyton mentagrophytes complex, were observed by light and electron microscopy. The structure of pseudo-cleistothecia, obtained by single spore culture of A. vanbreuseghemii, developed as a clump of hyphae producing microconidia which increased gradually in size. Echinulations appeared on the surrounding hyphae, which developed into peridial hyphae with characteristic constrictions. These pseudo-cleistothecia contained the microconidia. During the mating of A. vanbreuseghemii and Arthroderma simii, pseudo-cleistothecia structures developed from organs similar to the gametangia. These pseudo-cleistothecia contained interwoven hyphae but no microconidia.