abnormal axial mesoderm decreased axial mesoderm size 2013-11-14T11:49:43Z MP:0012272 MPheno.ontology csmith deficient axial mesoderm reduced axial mesoderm size reduced size or deficiency of the part of the middle of the three primary germ layers of the embryo which includes the prechordal mesoderm and the chordamesoderm and gives rise to the prechordal plate and to the notochord