Locomotion and scanning electron microscopic observations of primordial germ cells from the embryonic chick blood in vitro.

The locomotion of chick primordial germ cells (PGCs) in vitro was observed using 16-mm time-lapse microcinematography and 35-mm time-lapse film. The PGCs isolated from circulating blood of stage 14 to 16 embryos (Hamburger and Hamilton, 1951) were cultured on a substrate of mesenchymal feeder cells obtained from the dorsal mesentery of stage 40 embryos, using modified medium 199 containing 10% fetal calf serum. The PGCs were found to move actively and to show a tendency to move along the longer axis of the underlying cells. The velocity of PGC locomotion averaged 26 micron/hr and reached 58 micron/hr as a maximum. After observation, the PGCs were processed for scanning electron microscopy. They had a considerable number of microvilli about 0.2 micron in thickness and some cytoplasmic blebs on their surfaces. It was observed that the PGCs in the migrating phase adhered to the substrate with its filopodia only at the leading edge, while a large part of the cell appeared to be apart from the substrate.