Freeze-fracture study of human brain tumors.

This freeze-fracture study was performed in 3 astrocytomas, 6 glioblastomas, 2 ependymomas, 3 medulloblastomas, 1 cerebellar sarcoma, 3 germinomas, and 1 medulloepithelioma. The number of nuclear pores/mum2 nuclear membrane was not correlated with biological malignancy. Fracture faces A and B were discernible in nuclear, Golgi and rough endoplasmic reticulum (ER), mitochondrial surface, and plasma membranes. Fenestrae were evident in Golgi and ER membranes. The transitional zone of cristae from the inner surface membrane appeared as a circular hole and broken-off neck on faces A and B of the inner surface membrane, respectively. The decrease in number of membrane particles in the plasma membrane seemed to correlate with the frequency of metastases, and, in addition, the membrane particles appeared to cluster in glioblastoma, medulloblastoma, and medulloepithelioma. The gap junctions were abundant in astrocytomas, moderate in number in ependymomas and germinomas, and rare in glioblastomas, cerebellar sarcoma, and medulloepithelioma. Tight junctions were often found in germinomas and medulloepithelioma, and rarely in ependymomas.