Active locomotion of human primordial germ cells in vitro.

The locomotion of human primordial germ cells (PGCs) in vitro was observed using 16-mm time-lapse microcinematography. PCGs dissociated from 5- to 6-week human embryos were cultured in vitro using L-15 medium and human cord serum, and their movement on three artificial and two natural substrates was compared. Three-dimensional collagenous fiber nets reconstructed in the culture dish were found to be appropriate for PGC movement, although the cells did not migrate actively on any of the other substrates. The PGCs moved actively in an amoeboid fashion, extending pseudopodlike cytoplasmic processes toward the direction of movement. The direction of PGC locomotion was random. One PGC showed the most active motility; the velocity of the cell locomotion averaged 25 microns/h and it became extremely elongated, measuring 92 microns in its longer axis, whereas in the stationary state the PGC was rounded and measured 20 microns in diameter. Thus, the present study offers evidence that human PGCs can migrate actively.