Changes in the neural cell adhesion molecule patterns on the rat glial cell surfaces with development and contact formation in vitro.

In monolayer cultures of newborn rat hippocampal cells, immunogold-labelling at the electron microscope level was used to study quantitatively the neural cell adhesion molecule (N-CAM) arrangement on the surface of glial soma and processes on 5 and 12 days in vitro (DIV). Four corresponding samples of micrographs were formed. To quantify the labelling, a stochastic geometry approach was used. Spectra of lateral distances between labels as well as simulated images of the surface label arrangement (invisible in micrographs) were derived and compared. The data show that, on both 5 and 12 DIV, N-CAM density on the surface of processes is approximately 2 times higher than that in somata; 12-DIV cells showing a lower (approximately 25%) N-CAM surface density as compared with the 5-DIV cells. This suggests that N-CAM expression in glia surfaces decreases while the cells form contacts, and N-CAM sorting between soma and processes remains stable. The simulated topographies of the lateral N-CAM arrangement might highlight fundamental mechanisms that underlie formation of the neural network.