from The Century Dictionary.
- noun A primitive segment of the mesoderm of an embryo destined to become a muscle or series of muscles; a myocomma, myomere, or myotome. Also called
Sorry, no etymologies found.
The cells of the segment become differentiated into three groups, which form respectively the cutis-plate or dermatome, the muscle-plate or myotome, and the sclerotome (Fig. 64).
The cutis-plate is placed on the lateral and dorsal aspect of the myocl, and from it the true skin of the corresponding segment is derived; the muscle-plate is situated on the medial side of the cutis-plate and furnishes the muscles of the segment.
From its inner or median wall are developed the muscle-plate (mp, the rudiment of the trunk-muscles) and the skeletal plate, the formative matter of the vertebral column (sk).
This was afterwards replaced by a pair of internal lateral muscles, that developed from the middle wall of the coelom-pouches; we still find the first rudiments of the muscles arising from the muscle-plate of these in the embryos of all the Vertebrates (cf. Figures 1.124, 1.158 to 1.160, 2.222 to 2.224 mp).
The simple coelom-pouches divide by a frontal septum into two on each side; the dorsal pouch (episomite) forms a muscle-plate; the ventral pouch (hyposomite) forms a gonad.
B medullary tube, C chorda, C1 inner chorda-sheath, D visceral epithelium, E sub-intestinal vein. 1 cutis, 2 muscle-plate (myotome),