Quain's elements of anatomy . all or lens epithelium,and between them the hollow of thelens vesicle ; 7n, mesoderm surroundingthe secondary ocular vesicle, no scleroticor choroid yet formed ; vi, connectionof this with the vitreous body; iii,thin layer of mesoderm in front of thelens or rudiment of the cornea andl^upillary membrane ; e, portion of theeijithelium of the front of the eye. connective tissue and blood-vessels developed from meso-blastic elements are projectedfrom below, so as to furnish the materials for the formation of thevitreous humour and the blood-vessels which pass through
Quain's elements of anatomy . all or lens epithelium,and between them the hollow of thelens vesicle ; 7n, mesoderm surroundingthe secondary ocular vesicle, no scleroticor choroid yet formed ; vi, connectionof this with the vitreous body; iii,thin layer of mesoderm in front of thelens or rudiment of the cornea andl^upillary membrane ; e, portion of theeijithelium of the front of the eye. connective tissue and blood-vessels developed from meso-blastic elements are projectedfrom below, so as to furnish the materials for the formation of thevitreous humour and the blood-vessels which pass through it to thelens, and also to surround the lens with vascular and fibrous elements,out of which are produced the capsulo-jnqnllary memhrane, and pro-bably also the capsule of the lens. It results from the observationsof Lieberkiihn (No. 216) that in mammals the fold which produces theocular cup or secondary vesicle runs back into the stalk so as to fold inthe optic nerve for a considerable space, and by the simultaneous enclosme. Fig. 753. BTSNif:* Fig. 753. TRANSVERSE VERTICAL SECTION OF THE EYEBALL OF A HUMAN EMBRYO OF FOUR WEEKS. (From K(311iker). ^f. The anterior half of the section is ^r, the remains of the cavity of the primary opticvesicle ; j^3, the inflected part of the outer layer,forming tlie retinal pigment ; r, the thickened innerpart giving rise to the columnar and other struc-tures of the retina ; v, the commencing vitreoushumour within the secondary optic vesicle ; v, theocular cleft through which the loop of the centralblood-vessel, a, projects from below ; I, the lenswith a central cavity. of mesoblastic tissue thus to lead to the introduction of the central blood-vessels of the retina within the nerve. But in birds, according to thesame observer, no such infolding of the stalk occurs, so that in them thevessels are excluded from the nerve. The malformation termed cololonia
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Keywords: ., boo, bookcentury1800, booksubjectanatomy, booksubjecthumananatomy
