The cellular basis of Fundulus epiboly. Adhesivity of blastula and gastrula cells in culture

Abstract

The behavior of dissociated cells of blastula and early gastrula blastoderms of Fundulus heteroclitus was studied in cell culture. Blastula cells remain spheroid and lobopodial during the first 6 hours after culturing. Most early gastrula cells, on the other hand, flatten extensively on the glass substratum within an hour or two, indicating that they possess greater surface adhesivity. The correlation of cell flattening in vitro with the onset of epiboly supports the hypothesis that epiboly of the blastoderm is due in part to the activities of its individual constituent cells. Late blastula cells flatten more extensively with increased time in culture, when control eggs are beginning epiboly. This suggests that the process whereby cells increase in adhesivity within the blastoderm continues in culture. The results are discussed in relation to cell locomotion within the blastoderm and the mechanism of Fundulus epiboly, and a revised concept of epiboly is presented.