Studies on the biochemistry and morphology of freshly isolated and maintained rat hair follicles.

We have already shown that shearing can be used to yield large numbers of viable intact hair follicles. We now show that these follicles can be viably maintained on permeable supports for 7 days in vitro as determined by their adenine nucleotide contents, rates of [methyl-3H]thymidine and [U-14C]leucine uptake, [methyl-3H]thymidine autoradiography, patterns of keratin synthesis and light and electron microscopy. These studies, however, show that after 7 days maintenance the morphology of maintained follicles shows a closer resemblance to the telogen rather than the anagen follicle. We therefore conclude that the failure of previous attempts at maintaining hair growth in culture is due to hair follicles prematurely entering the resting stage of their hair growth cycle, possibly as a response to isolation.