. The development of the human body : a manual of human embryology. Embryology; Embryo, Non-Mammalian. 82 THE MESODERMIC SOMITES layer gradually extends more ventrally and displaces, or, more properly speaking, assimilates into itself, the membrana reuniens until finally the latter has completely disappeared. It is to be noted that no part of the voluntary musculature of the lateral and ventral walls of the neck and trunk is derived from the somatic layer; it is formed entirely from the myotomes which gradually extend ventrally (Fig. 51) and finally come into contact with their fellows of the
. The development of the human body : a manual of human embryology. Embryology; Embryo, Non-Mammalian. 82 THE MESODERMIC SOMITES layer gradually extends more ventrally and displaces, or, more properly speaking, assimilates into itself, the membrana reuniens until finally the latter has completely disappeared. It is to be noted that no part of the voluntary musculature of the lateral and ventral walls of the neck and trunk is derived from the somatic layer; it is formed entirely from the myotomes which gradually extend ventrally (Fig. 51) and finally come into contact with their fellows of the opposite side in the mid-ventral Fig. 51.—Diagrams Illustrating the History of the Gastral Mesoderm. dM, dorsal portion of myotome; gr, genital ridge; I, intestine; M, myotome, mr, membrana reuniens; N, nervous system; SC, sclerotome; Sm, somatic mesoderm; vm, splanchnic mesoderm; vM, ventral portion of myotome; Wd, Wolffian duct. Whether the voluntary musculature of the limbs is also derived from the myotomes is at present doubtful. It has been very generally believed that the myotomes in their growth ventrally sent prolon- gations into the limb buds which invested the axial core of mesen- chyme and eventually gave rise to the voluntary muscles. The actual existence of the prolongations of the myotomes and their conversion into the limb musculature has, however, not yet been observed and it is quite possible that the limb musculature may be derived from the axial core of somatic mesoderm from which the limb skeleton develops. The appearance of the mesodermic somites is an important. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original McMurrich, J. Playfair (James Playfair), 1859-1939. Philadelphia : P. Blakiston's son & co.
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Keywords: ., bookautho, bookcentury1900, bookdecade1910, booksubjectembryology
