annulus(redirected from Annular region)
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annulus[an´u-lus] (pl. an´nuli) (L.)
alternate spelling of anulus.
n. pl. annu·luses or annu·li (-lī′)
1. A ringlike figure, part, structure, or marking, such as a growth ring on the scale of a fish.
a. A ring or group of thick-walled cells around the sporangia of many ferns that functions in spore release.
b. The ringlike remains of a broken partial veil, found around the stipes of certain mushrooms.
annulusAny ring-like structure (e.g., mitral valve annulus).
annulusAny ring-like structure.
- the ring of cells in the moss or fern capsule which splits to allow the liberation of spores.
- a ring of tissue surrounding the stalk in the fruiting bodies of the BASIDIOMYCOTA fungi.