An electron microscopic histochemical and analytical X-ray microprobe study of calcification in Bruch's membrane from human eyes.

Transmission electron microscopy, electron microprobe analysis, high temperature microincineration, and electron microscopic histochemical procedures were used to study the electron-dense deposits characteristic of the macular aspect of aged human eyes. These inorganic deposits were rich in calcium and phosphorus and selectively removed by flotation on formic acid. The amorphous decalcified masses showed a significant sulfur peak and were readily stained with acidic phosphotungstic acid. The latter observations are indicative of the presence of organic matrical proteoglycan. Such data may be a further indication that proteoglycans are retained at sites of calcification.