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definitions

limb bud

n.
  1. A mesenchymal outgrowth covered with ectoderm on the flank of an embryo that gives rise to either the forelimb or the hindlimb.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.