The Effect of a Single Epilation on Successive Hair Eruptions in Normal and Hormone-Treated Rats

The study investigated the effects of hair plucking on hair growth cycles in normal and hormone-treated female rats. It was found that epilation generally advanced the next hair eruption unless performed just before a spontaneous eruption. Plucking club hairs from resting follicles led to a fixed interval before new growth, while plucking growing hairs resulted in a longer interval, influenced by the anagen stage at the time of plucking. Hormonal treatments like estradiol or propylthiouracil extended the interval to eruption, while spaying or thyroxine reduced it. Epilation consistently advanced subsequent eruptions, with the second eruption being more advanced than the first. The first post-epilation anagen phase remained unchanged, but the following resting phase was shortened, and later cycles were prolonged. There was some evidence of a systemic control mechanism attempting to resynchronize the cycles of epilated and non-epilated follicles, though complete synchrony was not achieved within three or four cycles.