NON-AMEBOID LOCOMOTION OF CULTURED MICROGLIA OBTAINED FROM NEWBORN RAT-BRAIN

The movements of cultured microglia obtained from newborn rat brain we re examined by video enhanced-differential interference contrast (VEC- DIC) microscopy. Active microglia measured 9.03 +/- 1.06 mu m in diame ter (mean +/- SD, n = 33; range, 7.03-10.36 mu m). The microglia appea red to become smaller with spread of lamellipodia. The short axis of a ctively moving microglia measured 7.03 +/- 0.49 mu m (n = 7). The lame llipodia were thin, transparent and developed rapidly around the cell body (maximal speed of extension, 4 or 5 mu m/s). When shear stress fr om the medium was applied to the surface of cultured cells, the microg lia swam with flat lamellipodia serving as sails in the stream. Sponta neous non-amoeboid movements of microglia were observed: they pivoted, circled and marched in various directions using their lamellipodia. T he angular speed of rotation was maximally 3 degrees/s. In 5 marching cells, the average speed (distance/s) was calculated at 1.01 +/- 0.54 mu m/s (ca. 60 mu m/min or 3.6 mu m/h).