Intramitochondrial Glycogen Particles in Rat Retinal Receptor Cells

In t rami tochondr ia l granules or bodies have been described by many investigators in various cell types. Al though the advanced techniques of electron microscopy in general have clarified the existence of several types of in t rami tochondr ia l components , and in some cases even their chemical characteristics (1, 2), the chemical na ture of most such substances is still unknown. Dur ing this electron microscope study of the normal ra t retina, a new type of particle was noted within the mi tochondr ia of the receptor cells. These in t rami tochondr ia l particles, unlike any of the known types, appear to be similar to .glycogen particles morphologically as well as histochemically. This note reports in t rami tochondr ial glycogen particles in ra t ret inal cells, and the identification of glycogen in a tissue section at the electron microscope level.