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7-dehydrocholesterol

[-dē-hī′drō-kə-lĕs′tə-rôl′, -rōl′]

n.

A provitamin present in the skin of humans as well as the milk of mammals that becomes vitamin D3 when exposed to ultraviolet light.

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.