chain of skeletogenic mesenchyme cell oral chain of skeletogenic mesenchyme cell oral chain of PMCs ventral skeletogenic mesenchyme chain The chain of skeletogenic mesenchyme cell that within the subequatorial skeletogenic mesenchyme ring links the two ventrolateral skeletogenic mesenchyme clusters on the oral side of the embryo. The ventral transverse rods will be deposited along this cellular strand. echinoderm_anatomy ventral chain of PMCs