The repair and maintenance of connective tissues is performed predominately by a mesenchymal cell known as a fibroblast. The activity of this cell is regulated, in part, by changes in the mechanical environment in which it resides. The authors have addressed some of the questions related to the fibroblast and how it responds to mechanical stimulation. An in vitro model, the 'culture force monitor', and its derivative, the tensioning culture force monitor have been developed enabling quantitative investigations to be performed on fibroblasts in a collagen lattice. Results have shown that a fibroblast can generate a force of approximately 10(-10) N, as a result of change in cell shape and attachment, while in a three-dimensional collagen lattice. Application of a physiologically similar mechanical load has shown that fibroblasts have the ability to maintain a tensional homeostasis of approximately 40-60 x 10(-5) N per million cells, change cellular morphology in a predictable manner and biochemically modify their resident environment.