Macroconidia are hyaline, multiseptate, variable in form, fusiform, spindle-shaped to obovate, 7–20 by 30–160 um in size, with thin or thick echinulate to verrucose cell walls.

Their shape, size and cell wall features are important characteristics for species identification.

Microconidia are hyaline, single-celled, pyriform to clavate, smooth-walled, 2.5–3.5 by 4–7 um in size and are not diagnostic for any one species.

The separation of this genus from Trichophyton is essentially based on the roughness of the macroconidial cell wall, although in practice this may sometimes be difficult to observe.

The keratinolytic properties that Microsporum cookei possesses suggests that the fungus can alternatively be used for recycling the large amount of industrial keratinic waste.