Are cells in solid tissues immobile? Mesonephric mesenchyme studied in vitro

Abstract

Fragments of mesonephric mesenchyme isolated from 3-day avian embryos were allowed to round up in vitro. Pairs of tissue fragments were then fused and maintained in suspension culture. For the purpose of identification of cells, fusions were made between chick and quail or tritiated-thymidine labeled chick and unlabeled chick tissue fragments. Mobility of cells was detected by the movement of cells across the interfaces between the individual tissue fragments of the fused tissue masses. Since, after three days in culture, numbers of cells from one fragment were usually present within the depths of its partner fragment, it is concluded that cells within solid pieces of mesonephric mesenchymal tissue show continued mobility. Since large amounts of extracellular material were not found in the intercellular spaces of cultured tissue fragments, it is concluded that cell surfaces serve as the principal substrata for motility. Motility in solid tissue masses is not a reflection of the generalized loss of contact inhibition which is characteristic of invasive cells; contact inhibition of ruffled membrane activity was observed in mesonephric mesenchyme cells cultured in monolayer culture.