Intramitochondrial Glycogen Granules in Digestive Cells of Hydra

Digestive cells of hydra contain accumulations of irregular particles, 200 to 300 A in diameter and of low density, that stain with lead hydroxide (11). These particles were observed in clear areas of hyaloplasm and were often partially or completely enclosed by mitochondria. Similar dense particles in the hyaloplasm of digestive cells have been identified as glycogen (7, 16), although no association with mitochondria was noted. However, some other electron microscopic studies have identified glycogen within the mitochondria of the silkworm prothoracic gland (2), of sperm (1), of retinal receptor cells (9), and associated with the surface of mitochondria of muscle (17). The present paper reports further on the relationship of particles to mitochondria and presents evidence that this material is particulate glycogen.