Crawling-like movements and polarisation in non-adherent leucocytes

Leucocytes, in an appropriate medium, are polarized and show movements both when floating in suspension and when settled on, but not attached to, a substratum. These movements are similar to those performed during locomotion but significant active locomotion on a plain surface is invariably accompanied by adhesion to the substratum as detected by reflection contrast microscopy. The results suggest that the polarisation and crawling-type movements represent a fixed action pattern which is performed independently of adhesion to the substratum.