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The mesoderm.

Relating to the mesoblast; as, the mesoblastic layer.

rincipally in biological terms, and signifying growth, formation; as, bioblast, epiblast, mesoblast, etc.

the digestive tract; distinguished from a schizocoele, which arises by a splitting of the mesoblast of the embryo.

spectively the outer covering and inner wall of the gastrula. A third layer of cells, the mesoblast, which is formed later and lies between these two, is sometimes included. -- Germinal membrane. (Biol.) Same as Blastoderm. -- Germinal spot (Biol.), the nucleolus of the ovum. -- Germinal vesicle, (Biol.) , the nucle…

The part of the mesoblast which gives rise to the connective tissues and blood.

The layer of the blastoderm, between the ectoderm and endoderm; mesoblast. See Illust. of Blastoderm and Ectoderm.

The nucleus of a cell; mesoblast. Agassix.

A portion of the mesoblast (of peripheral origin) of the developing embryo, the cells of which are especially concerned in forming the first blood and blood vessels. C. S. Minot.

Neurilemma. -- Primitive streak or trace (Anat.), an opaque and thickened band where the mesoblast first appears in the vertebrate blastoderm.

One of the primitive masses, or segments, into which the mesoblast of the vertebrate embryo breaks up on either side of the anterior part of the notochord; a mesoblastic, or protovertebral, somite. See Illust. of Ectoderm.

e cavity of the blastosphere. In the gastrula stage, the segmentation cavity in which the mesoblast is formed lies between the entoblast and ectoblast. See Illust. of Invagination. -- Segmentation nucleus (Biol.), the body formed by fusion of the male and female pronucleus in an impregnated ovum. See the Note under Pr…