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JANE L. COULOMBRE, ALFRED J. COULOMBRE; Lens Development. IV. Size, Shape, and Orientation. Invest. Ophthalmol. Vis. Sci. 1969;8(3):251-257.
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© ARVO (1962-2015); The Authors (2016-present)
The right lenses were removed from a group of chick embryos at five days of incubation. Each lens was replaced by two lenses from donors of the same age. The donor lenses were implanted so that their equatorial planes lay at right angles to the equatorial plane of the host lens which they replaced. These cases were studied at 14 days of incubation. The volume of such lens pairs became regulated to correspond with that of a single 14-day-old lens. Each lens of an implanted pair assumed the shape of half of a normal 14 day lens bisected by a plane including its axis. Thus, the combined shape of a lens pair came to match that of a single 14 day lens. The lens pairs became internally reorganized: (1) lens epithelial cells ivhich, at the time of implantation, had lain anterior to the plane defined by the edge of the eye cup continued to divide, and spread out to cover those exposed surfaces of the lens pair which lay toward the cornea; (2) those epithelial cells which were positioned toward the vitreous body enlarged and elongated to form lens fibers; (3) as a consequence of these events a new equatorial zone appeared which girdled the lens pair along the line of its contact with the cup margin; (4) in this fashion the orientation of the lens pair was readjusted in a manner appropriate for the host eye. These experiments demonstrate the existence of mechanisms which control the size, shape, and orientation of the developing lens. It is suggested that these mechanisms include an influence from the limbic mesenchyme which promotes cell elongation and cell packing, and a neural retinal influence which promotes enlargement of the lens cells as they form lens fibers.
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