Exogenous stimulations change nude mouse hair cycle pattern

The pattern of murine hair growth has been seen as an unpredictable and irregular process. In this study, nude mice were used to investigate the hair growth pattern and find the impact of exogenous stimulations on changing the hair growth pattern. We found nude mouse hair appeared in waves from the head to the posterior part of the back for the first time. Amongst all of the six groups, male nude mice had a more regular hair cycle pattern than females: from the head to the posterior part of the back. When there was no hair on the back of a nude mouse, we named this time the 'no-hair phase' and the opposite was the 'hair-existing phase'. Exogenous stimulations significantly elongated the hair-existing time and shortened the no-hair time but did not work on the hair growth pattern. For male mice, topical application of minoxidil created a shorter no-hair phase and a longer hair-existing phase than other treatment methods. For female nude mice, minoxidil had little more effect than a wound in shortening the no-hair phase. A wound was better than minoxidil in elongating the hair-existing phase in female nude mice, and this effect was indistinctive.