The development of the human body; a manual of human embryology . Fig. 255.—vSections through the Lens (A\ no h,™,., c WV TO THIRTv-0NE DAVS fN^ 0^PIGFFHMUBX 481 48: THE DEVELOPMENT OF THE HUMAN BODY. As early as the second month of development the lensvesicle becomes completely inverted by mesodermal tissuein which blood-vessels are developed in considerable num-bers, whence the investment is termed the tunica vascu-. Fig. 256.—Posterior (Inner) Surface of the Lens from an Adult SHOWING THE SUTURAL LINES.—(Rabl.) losa lentis (Fig. 264, tv). The arteries of the tunic are inconnectio
The development of the human body; a manual of human embryology . Fig. 255.—vSections through the Lens (A\ no h,™,., c WV TO THIRTv-0NE DAVS fN^ 0^PIGFFHMUBX 481 48: THE DEVELOPMENT OF THE HUMAN BODY. As early as the second month of development the lensvesicle becomes completely inverted by mesodermal tissuein which blood-vessels are developed in considerable num-bers, whence the investment is termed the tunica vascu-. Fig. 256.—Posterior (Inner) Surface of the Lens from an Adult SHOWING THE SUTURAL LINES.—(Rabl.) losa lentis (Fig. 264, tv). The arteries of the tunic are inconnection principally with the hyaloid artery of thevitreous humor (Fig. 262), and consist of numerous finebranches which envelop the lens and terminate in loops THE OPTIC CUP. 483 almost at the center of its outer surface. This tunic un-dergoes degeneration after the seventh month of develop-ment, by which time the lens has completed its period ofmost active growth, and, as a rule, completely disappearsbefore birth. Occasionally, however, it may persist to agreater or less extent, the persistence of the portion cover-ing the outer surface of the lens, known as the membranapupillaris, causing the malformation known as congenitalatresia of the pupil. In addition to the vascular tunic, the lens is surroundedby a non-cellular membrane termed the capsule. Theorigin of this structure is still in doubt, some observersmaintaining th
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectembryol, bookyear1902
