F13 DEFOLLICULATED: A HAIR CYCLE MOUSE MUTANT WHICH LOSES IST PELAGE FOLLICLES COMPLETELY

¹R.M Porter, ²J. Reichelt, ¹D. P. Lunny, ¹E. B. Lane, ³C. A. B. Jahoda an ²T. M. Magin. ¹Cell structure Research Lab, Anatomy & Physiology, University of Dundee, DD1 5EH. ²Dept. of Molecular genetics, University of Bonn, Bonn, Germany. ³Biological Sciences, University of Durham.

We describe a spontaneous mouse mutant which develops hair normally but then loses it. Preliminary histology indicated that by 1.5 years, the epidermis had become acathotic and showed no sign of any pelage or tail follicles (York, 1999). To improve breeding success and for future linkage studies these mice have been back-crossed with C57/BL6 mice. On this background hair loss begins at 4–5 weeks, first ventrally and along the flanks  and then dorsally from tail to head. This suggests that the hair loss may be occurring during anagen. Hair growth then re-occurs with replacement of a rudimentary coat bur after a second coat loss, hair is not regrown. Histology on paraffin sections of the epidermis from these mice indicates that at 5 weeks, when hairs are initially lost, most follicles are in anagen. At 8 months of age some hair follicles are still present indicating that regression of the hair follicle occurs in a gradual manner. No cysts or other abnormal hair follicle derived structures are observed. There appears to be a reduction in number of sebaceous glands. The meibomium gland is also reduced leading to corneal opacities in older mice.