The isolation of lipofuscin granules from bovine cardiac muscle, with observations on the properties of the isolated granules on the light and electron microscopic levels

Abstract

Summary Lipofuscin granules—intracellular pigmented structures increasing in amounts with the age of the individual—occur in a large number of tissues of a wide variety of species. Bovine cardiac muscle tissue has been used to work out methods for isolating lipofuscin granules in milligram quantities. The procedure involves centrifuging fresh tissue homogenates in sucrose density gradients and differential centrifugations. The isolated structures are identified as lipofuscin granules on the basis of their characteristics in transmitted light microscopy and by their histochemical properties. Electron microscopy is used to evaluate the relative purity of the fractions. Two lipofuscin granule populations with different density properties are recovered. Tentative results suggest that there is an ultrastructural difference between the granules of the two populations. Lipofuscin granules taken from different animals also vary in their density properties, which appear to be a reflection of biological variation. The ultrastructure of isolated lipofuscin granules is described. It is concluded that lipofuscin granule fractions with a high degree of purity can be obtained with the procedures employed.