Human anatomy, including structure and development and practical considerations . nfuse, and in this manner form a closed sac, the lens-vesicle. This remains for a time connected with thesurface ectoblast, but later becomes separated fromit and forms an isolated sac of epidermal tissue, which,by the proliferation of its cells, becomes converted into a solid structure and constitutes thecrystalline lens. At first the lens-vesicle fills the cavity of the optic cup completely, but withthe deepening of the latter, a space appears between its anterior wall and the lens-vesicle,which gradually widen
Human anatomy, including structure and development and practical considerations . nfuse, and in this manner form a closed sac, the lens-vesicle. This remains for a time connected with thesurface ectoblast, but later becomes separated fromit and forms an isolated sac of epidermal tissue, which,by the proliferation of its cells, becomes converted into a solid structure and constitutes thecrystalline lens. At first the lens-vesicle fills the cavity of the optic cup completely, but withthe deepening of the latter, a space appears between its anterior wall and the lens-vesicle,which gradually widens and forms the vitreous cavity. The space between the lens-vesicleand the ectoblast is invaded by a process from the surrounding mesoblast, which pushes infrom the side. From this ingrowth is developed the cornea, with the exception of the surfaceepithelium, and the stroma of the iris. Almost from the first appearance of the invagination of the primary optic vesicle, theinvaginated portion of the wall exhibits a marked tendency to proliferation of its cells. The Brain-vesicle. Part of frontal .section of head of early rabbitembryo, showing optic vesicles evaginated frombram-vesicle. / 30. DEVELOPMENT OF THE EVE. 1481 Fig. 123S. ^^ ^* •v,*-! /-
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Keywords: ., bookauthormc, bookcentury1900, bookdecade1910, booksubjectanatomy
