Ectopic regeneration of whiskers in the hooded rat from implanted lengths of vibrissa follicle wall.

Previous studies relating to the effect on whisker growth of removal of various components of the whisker follicle have shown that both after removal of the dermal papilla alone and after removal of as much as the lower third of the follicle, regeneration of new dermal papillae and then the generation of whiskers may occur (Oliver, 1966 a, b). Histological studies of this regenerative phenomenon revealed that the outer root sheath became a solid cord or rod of cells and that dermal cells, derived at least in part from the mesenchymal layer, aggregated over the proximal surface of the rod and eventually became the new dermal papilla. To determine whether the regenerative process was dependent on factors present in the local follicle environment on the upper lip, lengths of isolated follicle wall ('follicle tubes') composed of the outer root sheath and the adherent mesenchymal layer were transplanted as autografts to ascertain whether they could regenerate dermal papillae and fibres in another site.