The crystalline lens system : its embryology, anatomy, physiological chemistry, physiology, pathology, diseases, treatment, operations and after-changes ; with a consideration of aphakia / by Louis Stricker.

  • Stricker, Louis, 1863-
Date:
1899
Catalogue details

Licence: Public Domain Mark

Credit: The crystalline lens system : its embryology, anatomy, physiological chemistry, physiology, pathology, diseases, treatment, operations and after-changes ; with a consideration of aphakia / by Louis Stricker. Source: Wellcome Collection.

Provider: This material has been provided by UCL Library Services. The original may be consulted at UCL (University College London)

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    3° the ciliary body. The lens becomes encircled by what is termed its fibro- vascular sheath, derived in part from the central artery of the vitreous ami in part from the vessels growing in between the lens and the cornea. The portion of the inner layer of the secondary optic vesicle still in contact with the lens—that is, the pars ciliaris retinae—acquires adhesions to this sheath. Then, as the eyeball enlarges, it does so at a greater rate than the lens, so that a portion of the ciliary body which was in contact with the lens grow- away from it and the adhesions which have formed between them become stretched, and the cells forming them much elongated, until only fibres with nuclei lying on them can be distinguished, and ultimately the nuclei go. leaving only the delieate fibres of the suspensory ligament as we see them in the adult eye.'' As a result of the tension of these elongating fibres, the antero posterior diameter of the originally almost globular lens takes on its lenticular form. He also suggests that this mode of development may throw light on some of the congenital abnormalities. Collins, however, raises the whole question again, when he states that he was unable to definitely determine whether the cells which form these fibres are derived from the fibro-vascular sheath of the lens, hence mesoblas- tic, or from the cells of the inner layer of the secondary optic vesicle which form the pars ciliaris retinae, hence Epiblastie, or n part form one or in part the connective tissue class, hence of mesoblastic origin. CHAPTER II. THE GEOWTH OF THE LENS. In contradistinction to its period of foetal development, the growth of the lens may be said to begin at the time when the first lamellae of lens fihres which take their origin at the Equator, completely surround the proximal fibres which, as we have seen, grow in an axial directum ami form the original nucleus, the lens body of the second period, and press them away from the distal epithelium and the posterior capsule. From this time, up to birth this production of fibres, which one after the other elongate to reach a seam, goes on. During this period, the lens is almost globular, but owing to the presence of many film* which have not attained their hill length all of which cross the- equator, the equatorial diameter must he somewhat greater than the axial. Since the human lens at birth shows the same star figure as does a live months foetus, the first period of growth ex- tends from about the middle lo the close of foetal life