Scanning Electron Microscopy of Opaque and Transparent States in Reversible Calf Lens Cataracts

Abstract

The microstructure of transparent and opaque calf lenses was studied using scanning electron microscopy. Cells in opaque lenses are very similar to cells in transparent lenses. This demonstrates that opacification does not require major changes in the structure or relative arrangement of the lens cells. We have, however, observed numerous, characteristic flat patches on the membrane surfaces of cells in opaque lenses. We also used laser diffraction and measurement of light transmittance to establish that glutaraldehyde fixation does not alter the optical properties or the cellular organization of the lens tissue.

Phase separation in lens cytoplasm is genetically linked to cataract formation in the Philly mouse.

“…The transition in early stages of cataract development is associated with a phase separation in the lens cytoplasm (4)(5)(6). A phase separation is a low-energy mechanism of cytoplasmic restructuring that is reversible and is characterized by a temperature, Tc, at which the cytoplasm undergoes a transition from a transparent state to an opaque state (2,4,5,7). In the transparent state, short-range order in the organization of cytoplasmic protein allows the cytoplasm to exist as a single homogeneous phase (8).…”

Recovery of Membrane Potentials from Diamide-induced Depolarization in Frog Lens Fibers

“…These studies have been undertaken employing techniques of morphology [Clark et al, 1980], biochemistry [#ngg.v et al, 1977], and combined techniques of the two [Bernardini et al, 1981]. As reported here, measurements of membrane potentials of lens fibers can also be useful for the study of mechanisms underlying the recovery process after damage or cataract formation.…”

A quantitative microprobe analysis of elements in cortical and nuclear cells of the calf lens

“…This relationship was more firmly established by numerous studies of elemental composition in the transparent and opaque states of lenses (Fischer, 1933;Salit et al, 1942;Updegraff, 1932;Van Heyningen, 1969;Mackay et al, 1932;Hart et al, 1963;Bushell, 1975, 1976;Kinsey and Hightower, 1978;Swanson and Truesdale, 1971;Racz and Kellermayer, 1977;Adams, 1929). The importante of biologica1 elements is represented by findings that lens membrane structure and function are altered by changes in sodium and potassium levels (Shinohara and Piatigorsky, 1977;Patterson and Bunting, 1964;Delamere and Paterson, 1978) and that both cytoplasm and membranes are restructured by variations in calcium concentrations (Clark et al, 1980;Hightower and Reddy, 1982;Spector and Rothschild, 1973;Jedziniak et al, 1972). Recently, changes in phosphorylated constituents have been measured by nuclear magnetic reso-nance spectroscopy under conditions that produce cellular restructuring and opacity (Lerman et al, 1982;Greiner et al, 1982).…”

“…This opacity is produced by a cytoplasmic phase separation (Clark and Benedek, 1980a;Delaye et al, 1981). The phase separation is a low energy restructuring that produces opacity in the nuclear cells while the cortical cells remain transparent (Delaye et al, 1982;Benedek et al, 1979;Clark et al, 1980;Tanaka and Benedek, 1975;Zigman and Lerman, 1965;Tanaka et al, 1977). The phase separation is important because it is associated with the earliest stages of lens opacification leading to cataracts produced by X-irradiation ), galactosemia (Ishimoto et al, 1979, hypoglycemia (Tanaka et al, 1983), hereditary cataract (Tanaka, personal communication), and other conditions associated with altered elemental composition (Benedek et al, 1979).…”