An improved fixation technique for maintaining the fine structure of the nuclear zone of neonatal mouse lens

The fine structure of the nuclear zone of neonatal mouse lenses can vary considerably according to the fixation used. When normal neonatal mouse lenses are fixed in a commonly used chilled glutaraldehyde solution, the nuclear zone develops a grossly visible opacity, and irregular sized protein granules appear in the subsequent sections. Similar artifacts of aggregated irregular sized protein granules appear when cataractous mouse lens are conventionally processed. These artifacts can be avoided by soaking the lens in 0.15 M reduced glutathione solution for 10-15 min before fixation in a phosphate buffered 2% glutaraldehyde solution (pH 7.4) at 27-35 C. Normal lenses treated in this manner maintain translucency in the nuclear zone throughout the fixation-embedding procedure, and the resulting sections show finely uniform granularity with the cell membrane well preserved. Similarly processed nuclear portions of cataractous lenses of Nakano mice show uniformly aggregated protein granules, measuring about 350A in diameter. The cell membranes in the cataractous zone are also not interrupted.