STRUCTURAL AND ULTRASTRUCTURAL CHARACTERISTICS OF HUMAN PINEAL-GLAND,AND PINEAL PARENCHYMAL TUMORS

We have studied 20 pineal parenchymal tumors (PPT) and 4 normal or cys tic pineal glands both by light and electron microscopy and immunohist ochemistry with antibodies against glial markers [glial fibrillary aci dic protein (GFAP) and protein S-100] or neural/neuroendocrine markers [neurofilaments (NF), synaptophysin and chromogranin A]. Light micros copy revealed the cellular organization of pinealocytes in the normal gland and in different morphological types of pineal tumors (typical p ineocytomas, PPT with intermediate differentiation, mixed PPT exhibiti ng elements of both pineocytoma and pineoblastoma and pineoblastomas). Immunohistochemistry showed the presence of GFAP and protein S-100 in interstitial cells in nonneoplastic pineal gland. Cell processes were labeled with anti-synaptophysin and anti-NF antibodies. No immunoreac tivity was found for chromogranin A in non-neoplastic pineal gland. In pineocytomas, GFAP and protein S-100 were observed in interstitial ce lls. Synaptophysin and NF were present in the large rosettes of pineoc ytomas. Synaptophysin, NF and chromogranin A were present in pineocyto mas with a lobular arrangement of cells. Anti-chromogranin A immunorea ctivity was also seen in lobular areas of some PPT with intermediate d ifferentiation. Analysis of normal human pineal gland by electron micr oscopy showed the presence of vesicle-crowned rodlets (VCR or synaptic ribbons), fibrous filaments (F), paired twisted filaments but few den se-core vesicles (DCV) in normal pinealocytes. Tumoral pineal cells ap peared to differentiate