INTERACTIONS OF LIVING ASTROCYTES IN-VITRO - EVIDENCE OF THE DEVELOPMENT OF CONTACT SPACING

We have studied the behaviour of living, process-bearing astrocytes in vitro, observing groups of cells at daily intervals for up to 7 days. Each cell initially formed two processes, appearing bipolar in shape, and with further time in culture, grew additional processes and appea red stellate. As their processes grew, the interactions between astroc ytes underwent characteristic changes. While bipolar, the cells appear ed to avoid making contact, lying parallel to each other. As they beca me stellate, the astrocytes made extensive contact with neighbours, gr adually forming extended, contacting networks in which their somas wer e regularly spaced (as previously described). The interactions which l ed to the establishing of such arrays were also evident. If two cells were initially close or adjacent, they extended short processes to con tact each other; then, as their processes grew, their somas moved apar t, until they were separated by 60-120 mu m. If two cells were initial ly well separated, each directed processes towards the other until con tact was made, often with striking precision, and their somas then mov ed together, until they were separated by 60-120 mu m. These behaviour s of contact, separation, and approach caused astrocytes to form clust ers, within which their somas appeared regularly spaced, and may repre sent the interactions which occur among astrocytes during normal devel opment to produce the regularly spaced arrays of astrocytes described in earlier studies of intact central nervous tissue. (C) 1994 Wiley-Li ss, Inc.