Morphology and locomotion of individual epithelial cells in culture

The behaviour in culture of epithelial cells derived from chick embryo pigmented retina epithelium (PRE), corneal epithelium (CE) and epidermis has been studied using time-lapse cinemicrography. The analysis concentrated on the morphology and movement of individual isolated cells, lacking contacts with other cells, during a 24h period starting 1-3 h after the cells were plated out in primary cultures. Isolated cells from all three sources could change morphology and reversibly exhibited either a poorly spread or a well-spread morphology. While poorly spread, the different cell types all appeared similar and all blebbed vigorously. In contrast, while well spread, the cells did not bleb significantly but there were other differences between them. Well-spread CE cells were always polarized by the presence of a dominant leading lamella but well-spread PRE cells were always unpolarized. Well-spread epidermal cells exhibited both a polarized and an unpolarized morphology. The tendency of individual isolated cells to change morphology varied with cell type. PRE cells were the most stable. Nearly 80% of them retained the same morphology throughout the period of analysis and only 1% of them showed three or more changes in morphology during this period. In contrast, 22% of CE cells and 37% of epidermal cells showed three or more changes in morphology during the period of observation. Isolated cells of all three types spent a greater proportion of the time exhibiting a poorly spread morphology than they spent exhibiting any alternative well-spread morphology. The analysis revealed a relationship between the morphology of isolated cells and the speed of their locomotion. Only cells with a well-spread polarized morphology showed significant movement. CE and epidermal cells with this morphology moved three to four times faster than their counter-parts with a poorly spread morphology or, in the case of epidermal cells, with a well-spread but unpolarized morphology. Actively moving PRE cells were not seen and this correlates with the absence of cells with a well-spread polarized morphology from cultures of this type. These findings are discussed in the light of similar investigations of cell behaviour in other epithelial cell types and fibroblasts.