Fungal Morphology for the Clinical Laboratory

Definitions and Nomenclature:

Anamorph

Asexual or "imperfect" form of a fungus; for example, Scedosporium apiospermum is the anamorphic form of the teleomorph Pseudallescheria boydii

Annellide

A conidiogenous cell that extends and retracts as it produces conidia, often leaving a succession of scars or rings

Apophysis

A broadening near the apex of the sporangiophore, subjacent to the columella

Arthroconidia

Conidia arising from pre-existing cells in the mycelium; adjacent cells collapse to release the mature form; see, for example, Geotrichum

Ascospore

Sexual spore produced in a sac-like structure called an ascus

Biseriate

Phialide supported by metula; see, for example Aspergillus terreus. See also Uniseriate and Metula, below.

Blastoconidia

One of three types of vegetative "spore" arising directly from the vegetative mycelium; budding form, e.g. seen in yeasts

Cleistothecia

(singular cleistothecium) A large, round structure in which asci and ascospores form; see, for example, Sepedonium

Chlamydoconidia

Conidia arising from pre-existent cells in the hyphae, which thicken and enlarge; may be intercalary, sessile, or terminal

Columella

The swollen, dome-shaped tip of a sporangiophore that extends into the sporangium

Conidia

(singular conidium) Asexual "spores" of fungus

Conidiophore

Specialized hyphal element bearing conidia

Denticle

A narrow, delicate projection bearing a conidium or sporangiolum; see, for example, Cunninghamella

Holomorph

Taxonomic name including teleomorphic and anamorphic forms of a fungus; the name of the teleomorph also serves as the name of the holomorph

Hyphae

(singular hypha) The fundamental, threadlike structure of molds

Metula

(plural metulae) Structure below the phialide in some Penicillium and Aspergillus species; see for example Aspergillus terreus

Mycelium

(plural mycelia) The mass of filaments that constitutes the body of a mold; may be vegetative or aerial (reproductive)

Perithecia

Large, round to pear-shaped structure containing asci and ascospores; a small, round opening distinguishes this from Cleistothecia; see, for example, Chaetomium spp.

Phialide

A conidiogenous cell that produces conidia from within its apex, which does not increase in width or length during conidiogenesis

Rhizoid

Root-like, branched hyphae which usually extend into growth medium; found especially in Zygomycetes. See, for example, Rhizopus

Sporangia

A fruiting body which forms a closed sac; see, for example, Absidia , Rhizopus

Sporangiophore

A specialized hyphal element that bears the sporangium

Sporodochia

A clump of conidiophores; see, for example, Epicoccum

Stolon

Horizontal hyphae growing along the surface of growth medium; runner

Teleomorph

Sexual or "perfect" form of a fungus; see Anamorph and Holomorph, above

Uniseriate

Phialide forming directly on vesicle; as, for example, Aspergillus fumigatus. See also Biseriate, above.