ADVANCED ELECTRON MICROSCOPICS OF CRYSTALLINE LENS

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The long term objective is to gain a comprehensive qualitative and quantitative knowledge of primate (monkey, baboon and human) and lower vertebrate lens morphology. Specifically, advanced electron microscopic techniques (stereo SEI-SEM and BEI-SEM, stereo BEI-TEM and HVEM and freeze-etch replication will be used to assess various parameters of vertebrate lens fiber cell morphology as a function of topography and age. Correlative stereo SEI-SEM, BEI-SEM, BEI-TEM and light microscopy will be used to examine; 1. the surface and internal morphology, shape, size, and distribution of interdigitations, microvilli and ridges of lens fiber cells; 2. the total membrane surface area of lens fiber cells in growth rings as a function of age will be determined from spheroidal geometry formulas utilizing measurements of fiber thickness, lens equatorial diameter and lens antero-posterior diameter and incorporating the additional amount of membrane surface area contributed by interdigitations, microvilli and ridges; 3. the alteration of primate lens suture morphology from y suture to star suture will be examined as a function of growth ring age. From these findings, computer reconstructions of primate lenses will be made to determine the age related alterations in the structural pattern formed along the primate lens polar axis through which light rays are transmitted; and 4. the contribution of cell-to-cell fusion to the ordered structure of primate lenses. Correlative BEI-SEM and SEI-SEM and STEM and BEI-TEM will be utilizing selective staining of specific lens fiber cell components will be used to qualitatively examine; 1. the interlocking pattern between microvilli and ridges on primate lengs fiber cells; 2. localization and identification of the internal cytoskeletal components of lens fiber cell interdigitations; and 3. localization of fusion zones and identification of their internal cytoskeletal components. Freeze-etch replication will be used to determine the following parameters of lens fiber celll morphology; 1. the morphology, size, number and distribution of communicating junctions; 2. the morphology, size and number of communicating junctional IMPs; 3. the morphology, size and number of non-junctional IMPs. The importance of such studies is derived from the fact that alterations in lens morphology have been noted in all types of cataract. These studies will aid in establishing the norms for future comparative studies of lens morphology alterations heralded by changes in lens biochemistry and physiology during cataractogenesis.