annulus (redirected from annulus sclerae)

an·nu·lus  (ny-ls)

n. pl. an·nu·lus·es or an·nu·li (-l)

1. A ringlike figure, part, structure, or marking, such as a growth ring on the scale of a fish.

2.

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.

3. Mathematics The figure bounded by and containing the area between two concentric circles.

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[Latin nulus, ring, diminutive of nus.]

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annulus  (ny-ls)

Plural annuluses or annuli (ny-l)

1. A ringlike figure, part, structure, or marking, such as a growth ring on the scale of a fish.

2. A ring or group of specialized cells around the sporangia of many ferns. By changing shape in response to variations in humidity, it breaks open the sporangium and then releases the spores with a whipping motion.

3. The ringlike remains of a membrane (called a veil), found around the stipes of certain basidiomycete mushrooms. The presence or absence of an annulus is often used to identify the species of an individual mushroom.

4. The figure bounded by and containing the area between two concentric circles.

Thesaurus

Noun	1.	annulus - a toroidal shape; "a ring of ships in the harbor"; "a halo of smoke" anchor ring, doughnut, halo, ring fairy circle, fairy ring - a ring of fungi marking the periphery of the perennial underground growth of the mycelium toroid - the doughnut-shaped object enclosed by a torus
	2.	annulus - (Fungi) a remnant of the partial veil that in mature mushrooms surrounds the stem like a collar skirt Fungi, fungus kingdom, kingdom Fungi - the taxonomic kingdom including yeast, molds, smuts, mushrooms, and toadstools; distinct from the green plants plant part, plant structure - any part of a plant or fungus partial veil - membrane of the young sporophore of various mushrooms extending from the margin of the cap to the stem and is ruptured by growth; represented in mature mushroom by an annulus around the stem and sometimes a cortina on the margin of the cap