A quantitative analysis of intramembranous particles during the development of neuroblastoma X glioma hybrid cells.

The process of neural differentiation of neuroblastoma X glioma hybrid cells (NG108-15 cells) was studied by freeze-fracture electron microscopy. The distribution of intramembranous particles (IMPs) was random and their density increased in both P-, and E-face of the plasmalemma when the membrane excitability developed. Undifferentiated cells grown in growth medium for 2-6 days had an average of 1300-1500 IMPs/micron2 in the P-face and 250-300/mu 2 in the E-face. After the cells were differentiated with dBcAMP for 1 week, the density of IMPs was 2600/micron2 in the P-face and 540/micron2 in the E-face. The analysis of size distribution showed the increase of the number of medium (7.5-10 nm) and large (greater than 10 nm) particles. The slight increase of large particles was observed in the case of differentiated N18TG2 (the parental neuroblastoma clone) cells. Treatment with dBcAMP did not affect the number and the size distribution of IMPs in the C6BU1 (the parental glioma clone) cells.