An outgrowth on the lateral trunk of the embryo that develops into a limb. The limb bud is divided into ectoderm and mesenchyme[cjm, modified from MP]. [ http://en.wikipedia.org/wiki/Limb_bud https://www.worldcat.org/search?q=bn%3A9780878932504 https://orcid.org/0000-0002-6601-2165 ]