Membrane structures of human oligodendroglioma.

Plasma membrane particles of four human oligodendrogliomas were distributed at random, and their average number per micronm2 plasma membrane was 1090+/-233 on face A and 230+/-46 on face B. Gap junction was occasionally visible, usually small in size and composed of a polygonal aggregate of several subunits: isodiametric particles, about 70-80 A in diameter, on face A and pits, about 30-40 A in diameter, on face B. Tight junction in two oligodendrogliomas was characterized by a meshwork of circular or ramifying crests on face A and complementary furrows on face B. It was often continuous in distribution, consisting of 5 or more strands. In addition, many particulate structures, occasionally fibrillar ones, of ridge materials were often visible in the bottoms of furrows, and a few particles were scatteredly found on the tops of crests. The ridge materials, if added together on crests and furrows, were linearly continuous in some case and discontinuous in other.