Growth and viability of secondary hair follicles of the Angora goat cultured in vitro.

The viability of isolated secondary anagen hair follicles from Angora goats was studied in an in vitro tissue culture system. Intact hair follicles were isolated from the dermal layer singly or in groups using watchmakers' forceps under a dissecting microscope following removal of both the epidermis at the basal layer and subcutaneous fat layers using a scalpel blade. The connective tissue sheath surrounding the follicle and the dermal papilla in the bulb were left intact. The isolated follicles were maintained floating in supplemented Williams E medium and showed significant increases in hair shaft length over 96 h. The viability of the cultured hair follicles was verified by the findings that (1) the rate of hair shaft elongation was similar to that occurring in vivo; (2) the pattern of DNA synthesis observed by autoradiography of [methyl-3H]thymidine uptake was maintained in the isolated follicles throughout culture; (3) the ATP content was significantly higher in growing follicles compared with that observed in freshly isolated follicles; and (4) Feulgen-stained preparations of fresh and maintained hair follicles confirmed the retention of mitotic activity in the matrix cells of the bulb for a maximum of 120 h of maintenance.