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In order to understand the factors determining the length of fibroblasts, three cell lines (mouse embryonic fibroblasts plus human fibroblast lines AGO 1523 and M19) were cultivated on the usual planar substrate (glass) and on specially prepared narrow linear strips of the same substrate, where the cells could spread only linearly. Morphometric measurements showed that the average length of cells of each type on the ‘unidimensional’ strips was no different from that on the usual ‘bidimensional’ substrate. The addition of colcemid significantly decreased cell length on both substrates, whereas cytochalasin D increased the length. We concluded that fibroblasts have an intracellular mechanism maintaining a relatively constant average cell length. This mechanism may involve the dynamic balance of centripetal and centrifugal forces developed by two cytoskeletal systems: the microtubules and the actin-myosin cortex. Three epitheliocyte cell lines (rat IAR2, canine MDCK and bovine FBT) were tested but, in contrast to fibroblasts, they did not maintain similar cell lengths on the usual substrate and on the linear strips, suggesting that control of length is cell-type-specific.

The percentages of cells with different types of cell surface relief were determined in cell suspensions derived from monolayer cultures. Primary cultures of rat embryo fibroblasts (REF) and cell lines REF (LT) and REF-1, immortalized cells of which preserved normal phenotypic characteristics of the initial primary culture REF, as well as morphologically transformed tumorigenic lines REF (LT) ras and REF-2EJ were studied. In REF suspensions the cells with the blebbed type of surface relief were shown to be predominant as compared with those with microvillus relief whereas cell suspensions derived from both immortalized and fully transformed cultures display the reverse ratio of cells with those types of surface relief. Therefore, the pattern of cell surface relief in cell suspensions derived from fibroblastic monolayer cultures may serve as a morphological marker of the initial stage of neoplastic transformation-immortalization when typical morphological signs of cell transformation are not yet manifested in monolayer cultures.