Microscopic Morphologic Features of the Mold Forms of Various Dimorphic Fungi

The spiked (echinulate) macroconidia seen in Image below is characteristic of the mold form of Histoplasma capsulatum.
Histoplasma capsulatum macroconidia

Histoplasma capsulatum macroconidia

Histoplasma capsulatum spiked macroconidia

Histoplasma capsulatum spiked macroconidia


The mold form of Coccidioides immitis (Image below) is characterized by the production of arthroconidia that appear alternate staining because each cell is separated by an empty space. When mature, each arthroconidium is swollen centrally, giving a barrel appearance.

Coccidioides immitis

Coccidioides immitis

Coccidioides immitis arthroconidia

Coccidioides immitis arthroconidia


Blastomyces dermatitidis produces spherical or oval conidia, each supported by an individual conidiophore (“lollipop“)

Blastomyces dermatitidis

Blastomyces dermatitidis

Blastomyces dermatitidis lolipop like macroconidia

Blastomyces dermatitidis lolipop like macroconidia


The mold form of Sporothrix schenckii is recognized by the production of tiny microconidia that are arranged around the tip of a delicate conidiophore as petals on a daisy flower.

Sporothrix schenckii

Sporothrix schenckii

Photomicrograph of Sporothrix schenckii

Photomicrograph of Sporothrix schenckii

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