Three Types of Cytoplasmic Granules in Cardiac Muscle Cells of Cynomolgus Monkeys (Macaca fascicularis)

Ceroid, lipofuscin, and hyaline-type intracytoplasmic granules found in cardiac muscle cells of cynomolgus monkeys were studied using histologic, histochemical, and fluorescent microscopic techniques. The studies indicated that the ceroid granules contained an insoluble lipid as well as a component that was stainable with Luxol fast blue and Mallory's phloxine stain for hyaline. Lipofuscin granules had staining reactions characteristic of the classical age-related pigment. Hyaline granules were devoid of lipid component and were distinctly different from either ceroid or lipofuscin. All three types of granules were located at the poles of cardiac muscle cell nuclei.