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 (mĕz′ə-dûrm′, mĕs′-)
The middle embryonic germ layer, lying between the ectoderm and the endoderm, from which connective tissue, muscle, bone, and the urogenital and circulatory systems develop.

mes′o·der′mal, mes′o·der′mic adj.
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
References in periodicals archive ?
S: normal stem cell; E: tumor of the endodermic origin; M: tumor of the mesodermic origin; and EC: tumor of the ectodermic origin.
DIFFERENTIAL DIAGNOSIS: D/D fall into three groups of developmental errors-those of neurogenic origin-the gliomas, neurofibromas and encephaloceles, those of ectodermic origin-the pilonidal sinus and those of mesodermic origin-the hemangiomas.
Histological examination revealed a heterogeneous entity consisting of two areas: a cystic and a solid one, both comprising a randomly disposed mixture of tissues with ectodermic, mesodermic, and endodermic origins, with histological structure different from that of the filum terminale (Fig.