Although current physiological findings imply that the mammalian pineal organ liberates an antigonadal agent, microscopic examinations of this organ have afforded little information regarding the possible storage and release of such a substance. Since it is known that light deprivation for six weeks results in pineal-induced atrophy of certain reproductive organs in adult golden hamsters, one might expect that any morphological manifestations of this activity in the pineal organ would be enhanced in hamsters which had heen deprived of light for that length of time. A comparison at the ultrastructural level of pineal glands from normal and experimentally blinded hamsters revealed that pineal cells from the blinded animals exhibited a greater number of vesicles and contained complex membranous whorls. The possible significance of the vesicles and lamellar whorls is discussed in terms of similar structures found in other tissues. A feature common to pineal tissue of both the normal and experimental hamsters was the apparent cellular segregation of two morphologically distinct types of mitochondria. Pinealocytes containing small, cristaform mitochondria were designated as P1 cells; those containing larger mitochondria characterized by a dense, plexiform array of cristae were designated as P2 cells.
Download Full PDF Version (Non-Commercial Use)