HISTOLOGY 



143 



ordinarily scattered throughout the interior of the fiber, but in higher 

 vertebrates the nuclei are at the surface of the fiber as if crowded out of the 

 deeper regions by the closely packed myofibrils (Fig. 104). Probably 



port!S;r;;;!ra11bt"Tet4^""t"- .^^°"'' '" '°^^^^''^^-' action, showing small 

 He at the su^aTiAt^^tl^V^or^^^^^^ Nuclei 



however, the fiber is the product of a single mesoderm cell of the embryo 

 and many nuclei are derived, by repeated divisions, from the original 

 mesoderm nucleus. The fiber, therefore, is a syncytium rather than a cell. 



. ! Tf °^ '^'^^'"^ ^^^'^ ^'^ "^"^h coarser than those of 



unstriated fibers. They are imbedded in a peculiar fluid sarcoplasm 



