Ability to culture dermal papilla cells from red deer (Cervus elaphus) hair follicles with differing hormonal responses in vivo offers a new model for studying the control of hair follicle biology.

Red deer stags annually grow two distinct seasonal coats, a winter coat and a summer coat; in addition, they produce a mane during the breeding season when plasma testosterone levels are high, which is replaced by the short neck hairs of the summer coat when testosterone levels are low. As two very different hair types are produced from the same follicle under hormonal regulation, they offer an interesting model for studying the effects of hormones, particularly androgens, on mammalian hair growth. Since the dermal papilla of the hair follicle has a regulatory function and is probably the site of androgen action, we have investigated whether cells from the dermal papilla can be readily cultured from various types of red deer follicles; as the follicular connective tissue sheath may regenerate a new papilla in vivo, this was also examined. Individual dermal papillae and lower portions of the connective tissue sheath were microdissected from mane and flank follicles of red deer stags during the winter breeding season and from the summer coat during the nonbreeding season. Primary cultures were established from isolated dermal papillae, connective tissue sheath and dermal explants, subcultured and reestablished after freezing. Deer dermal papilla cells resembled sheep cells; they displayed a polygonal shape and irregular organisation, but did not form aggregates in contrast to human and rat vibrissa cells. Connective tissue sheath cell morphology was intermediate between that of dermal papilla cells and dermal fibroblasts. However, all three cell types derived during the breeding season grew at a much faster rate than the same cells derived during the nonbreeding season. Therefore, primary cell lines can be fairly readily derived from deer hair follicles. Since the red deer stag offers both androgen-dependent neck (mane) and control flank follicles in the breeding season, plus control nonbreeding season neck follicles, this means that stag follicular cells, particularly the dermal papilla cells, appear to offer a unique novel model system for the study of the hormonal regulation of hair growth.