[Onychomycoses caused by moulds].

The authors studied in vitro and in vivo the invasion of the nail keratin by saprophytes. This invasion takes palce in the same way in both cases: mycelian filaments and spores penetrate in the hyponychium, filaments penetrate in the upper part of the tablet, filaments and, as far as some saprophytes are concerned, 'boring hyphae' penetrate in the lower part of the tablet. Those ways of invasion are responsible for the clinical pictures (onychomycosis, pachyonychia, leuconychomycosis). Electron microscopically the mycelian filaments appear to be both intercellular and intracellular. The authors insist in the importance of the criteria of evaluation which allow us to establish the saprophytic origin of onychomycosis.