spherulin

spher·u·lin 'sfir-yə-lən, 'sfer- n an antigen that is derived from a fungus of the genus Coccidioides (C. immitis) while in its endospore-producing phase and that is used similarly to coccidioidin

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sphe·ru·lin (sfērґu-lin) a skin test antigen prepared from spherule-endospore phase Coccidioides immitis organisms; it detects almost all persons who are coccidioidin-positive, as well as a group of coccidioidin-negative persons with previous C. immitis exposure. Cf. coccidioidin.