Glial precursor cells in the adult human brain

Oligodendrocytes, the glial cells responsible for laying down and maintaining myelin sheaths in the central nervous system, were first described only 75 years ago. The lineage of these cells, and its relationship with that of the second type of macroglia, the astrocyte, was much studied in vivo and in situ in the rodent over the next 60 years. In the early 1980s, progress in oligodendrocyte biology was markedly amplified by the application of tissue culture techniques-not without some element of controversy, although this is now largely resolved. Oligodendrocytes have always been given more attention than many other cells as a consequence of their role as a key target in human demyelinating diseases; in fact, few studies of rodent oligodendrocytes fail to draw conclusions regarding multiple sclerosis. Now, however, techniques for studying human glia and their lineage more directly have emerged, and differences in rodent and human oligodendrocyte biology are becoming apparent. It is increasingly clear that some caution must accompany the uncritical extrapolation of rodent experimental data to human oligodendrocyte biology and, indeed, to human disease.