ABSTRACT
The distribution of the extracellular matrix molecules fibronectin, laminin and entactin was studied in frozen sections of 
-day mouse embryos in order to relate their presence to neural crest cell migration. It was found that all three components were present in basement mem-branes, laminin and entactin being mainly restricted to these. Fibronectin was present at high levels in basement membranes and extracellular spaces throughout the embryo, including the regions of neural crest cell migration. Fibronectin is known to affect migration in a variety of cell systems, so its presence in the.embryo at the time of migration may indicate that it is influencing cell movement. This influence is likely to be via the cell surface through interactions with other matrix components such as glycosaminoglycans, and possibly entactin and laminin.
