C1   MORPHOLOGIC FEATURES OF HAIR FIBERS IN NORMAL AND MUTANT LABORATORY MICE

¹Sundberg J.P., ¹Bechtold L.S., and ²King L.E. ¹The Jackson Laboratory, Bar Harbor, ME, U.S.A and ²Dept. of Dermatology, Skin Disease Research Center, Vanderbilt University and Bureau of Veterans Affairs, Nashville, TN, USA

Laboratory mice, being mammals, are covered with hair.  Traditional studies have characterized four major hair types on the body of mice: guard, awl, auchene, and zigzag hairs.  Other hair types include the vibrissae (so-called whiskers) and cilia (eyelashes).  Systematic evaluation of skin reveals many more unique hair types that are rarely described including several distinct types on the ears, tail, perianal region, and muzzle.  Biologically distinct hair follicle and fiber types can be identified as sequellae to various mutations that result in alopecia due to either selective loss of sparing of hair types.  Examination of the hair fibers themselves by light and scanning electron microscopy reveals mutant phenotypes with fibers having excessive length, excessive surface debris, pili canaliculi, longitudinal striations, cuticle defects, pili torti, fractures (trichorrhexis nodosus or tirchoclasis) and longitudinal fissures (pili bifurcati).  Electron micrographs will be used with discussions focused on glass microscope slide projections illustrating these various mutant phenotypes in laboratory mice with comparison, where appropriate with homologous human case material.