Glial fibrillary acidic (GFA) protein-containing cells in the human pineal gland.

The development of human pineal astrocytes was studied in a prospective autopsy series of 115 cases with an age range of 24 weeks of gestation to 91 years. Pineal glands selected from cases with postmortem intervals of one to 24 hours were fixed in Bouin's fluid and immunostained using the peroxidase-antiperoxidase technique and an antiserum against human glial fibrillary acidic (GFA) protein. In adults, scattered, mostly angular and strongly-positive cells and processes were present. A few primary processes emanated from each astrocyte which abruptly subdivided into several secondary ones, creating a pervasive interstitial network of fibers which surrounded almost every individual pinealocyte. Astrocytic endfeet formed a limiting lamina at the periphery of the gland and a barrier between perivascular spaces and the pineal parenchyma. At 24 weeks of gestation, occasional punctate staining, mainly around vessels, was present in the pineal body, while in the surrounding white matter there was already pronounced astrocytic differentiation. Around 32 weeks of gestation, well-formed astrocytes and a weakly staining network of their processes appeared in differentiated areas of the pineal gland. Both astrocytes and their interstitial network of processes became more prominent with advancing age. There was no astrocytic hypertrophy or hyperplasia around calcified deposits. Rosenthal fibers stained negatively for GFA protein. These findings emphasize the significance of the astrocytic participation in the structure of the human pineal gland throughout life.