| Abstract: | The behaviour of chick embryo pigmented retina epithelial (PRE) cells has been studied in living and fixed cultures. Isolated PRE cells lacking contacts with other cells were characteristically only poorly spread upon the substrate, blebbed vigorously and lacked leading lamellae. PRE cells incorporated into islands or sheets of cells were extensively spread upon the substrate, lacked blebs and displayed typical leading lamellae if marginally positioned in an island. Observations of living cultures demonstrated that within 3 h of establishing contact with an island of cells a previously isolated PRE cell lost the morphology characteristic of isolated cells and became indistinguishable from its neighbours in the island. Measurements of the area of substrate occupied by single cells and cells in 2-cell islands suggests that similar changes occur as two cells make contact to form a 2-cell island. The evidence suggests that these changes are a direct response to the establishment of a cell-cell contact and I propose that the phenomenon be termed ‘contact-induced spreading’.Contact-induced spreading is not an ‘all or none’ phenomenon since isolated PRE cells can spread extensively and cease blebbing in the absence of cell contact. However a given isolated PRE cell spends only a very small proportion of its time displaying this well spread morphology and therefore at any time the majority of isolated PRE cells display the poorly spread morphology.The possible relationship between contact-induced spreading and other cellular interactions known to be dependent on cell-cell contact is discussed. |
