annulus(redirected from atrioventricular annulus)
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Any ringlike anatomical part.
An elastic ring of cells between the operculum and the mouth of the capsule in mosses.
A line of cells, partly or entirely surrounding the sporangium in ferns, which constricts, thus causing rupture of the sporangium to release spores.
A whorl resembling a calyx at the base of the strobilus in certain horsetails.
The ringlike figure that lies between two concentric circles.
A ring of tissue representing the remnant of the veil around the stipe of some agarics.