Metablastic: relating to the ecto- or meta-blast or ectoderm.
Ectoblast: the outer wall of a cell; the ectoderm or epiblast.
The outer is the Ectoderm and the inner is the Endoderm or Hypoblast.
The ectoderm retains its ciliation only in the sensory organs.
It consists of three layers: ectoderm, endoderm, and mesoderm.
Ectoderm, the tissue in an adult derived from the epiblast (which see), 19.
Amongst other structures which arise from the important layer of ectoderm are the teeth.
The medusoids have a muscular velum of ectoderm and mesogloea only.
The external layer, or ectoderm, is made up of cells, and contains also muscular and nervous elements.
In the course of development, however, cells from the ectoderm and endoderm may migrate into it.