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

Abstract

A method is described for isolating and removing lengths of follicle wall, composed of the inner root sheath, outer root sheath and mesenchymal layer, from vibrissa follicles. These segments of follicle wall were transplanted into ear skin and, in one case, into an ovarian capsule. Seven of the thirteen implants originally dissected from the lower third of the follicle produced short whiskers up to 6 mm in length. Two further implants had also regenerated dermal papillae but not whiskers. The dermal papillae regenerated at the proximal end of the implants and appeared to derive from cells from the mesenchymal layer. None of the four implants obtained from above the lower third of the follicle regenerated dermal papillae or produced whiskers. The outer root sheaths of all of the implants which did not regenerate papillae or whiskers did, however, maintain their typical histological character. The possibility that maintenance of the implants was dependent on the presence of the mesenchymal layer is discussed. Whisker growth from transplanted lengths of follicle wall logically isolates the outer root sheath and/or the mesenchymal layer as the essential prerequisites for papilla regeneration.