Abstract

The commencement and course of cell proliferation is described in proanagen hair follicles of ferrets. Initiation of autumn fur growth was synchronised in 32 animals using melatonin implants. Skin samples containing S-phase cells labelled in vivo with bromodeoxyuridine were collected from groups of four animals up until the time of development of metanagen follicles at 14 days post-implant. Cells were visualised by an indirect immunocytochemical method and counts made of proliferating cells in the hair germ, epithelial strand/outer root sheath, connective tissue sheath and dermal papilla. Telogen follicles showed no labelling in all four tissues until 4 days after melatonin implant. The largest number of proliferating cells were in the hair germ, which formed the new fibre and inner root sheath. The cell labelling index for this tissue remained high at 14 days post-implant. In other tissues, cell proliferation reached peaks during mid to late proanagen, then declined as the metanagen state was reached. These results indicate that some key signalling events controlling ferret hair growth occur between 0 and 4 days after the melatonin implant, and illustrate the separate processes of follicular regeneration and fibre growth occurring in proanagen follicles.

JG, Thompson, AC Simpson, PA Pugh, LT McGowan, RW James, DK Berg, SR Payne, and HR Tervit

Proceedings of the New Zealand Society of Animal Production, Volume 52, , 255-256, 1992