Quain's elements of anatomy . Fig. 721.—Transverse sectioit op an embrto chice of the latter half of the SECOND DAT, AT THE PLACE WHERE THE A^ERTEBEAL SOMITES CEASE. \^ (FrOHL Kolliker.)no, dorsal ridges ; rf, medvillary groove, or canal beginning to close; tiwp, proto-vertebral plate ; sp, lateral plate of the mesoMast ; A, epiblast ; eld, hypoblast; ao,primitive double aorta ; sp, commencement of division of the mesoblast which forms thebody-cavity. spherical, but they afterwards become elongated and spindle-shaped,and increase rapidly by multiplication. They represent at first thegrey subst
Quain's elements of anatomy . Fig. 721.—Transverse sectioit op an embrto chice of the latter half of the SECOND DAT, AT THE PLACE WHERE THE A^ERTEBEAL SOMITES CEASE. \^ (FrOHL Kolliker.)no, dorsal ridges ; rf, medvillary groove, or canal beginning to close; tiwp, proto-vertebral plate ; sp, lateral plate of the mesoMast ; A, epiblast ; eld, hypoblast; ao,primitive double aorta ; sp, commencement of division of the mesoblast which forms thebody-cavity. spherical, but they afterwards become elongated and spindle-shaped,and increase rapidly by multiplication. They represent at first thegrey substance, or the nerve-cells and non-meduUated fibres. The Fig. Fig. 722.—Transverse section op the embryo chice in the latter half op theSECOND DAT, IN THE REGION OP THE proto-vertebrjs. ^1^. (From Kolliker.) m, medullary tube ; Ji, epiblast now separated from the medullaiy inflection; uw,proto-vertebral mass ; hp, parietal or somatic mesoblast ; dfp, visceral mesoblast; ^5,pleuro-peritoneal or body-cavity between these two layers ; ch, notochord; ao, aorta stilldouble ; ent, hyxjoblast. cyHndrical cells which, from the first, line the whole canal, remain per-manently in some parts of it, and frequently present the ciliatedstructure. THE SPINxVL COED. The internal grey substance of the spinal cord is first formed; thewhite substance is produced later on the exterior. The sides acquireconsiderable increased thickness, while the dorsal and ventral parts THE SPINAL CORD. 821 remain comparatively thin, so that the cavity assumes in section the ap-jDearance of a sht, which becomes gradually narrower as the lateralthickening increases; and at last th
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Keywords: ., boo, bookcentury1800, booksubjectanatomy, booksubjecthumananatomy
