Dermatology Online Journal

Nail Diseases: Search for Mouse/Human Analogues.
John P. Sundberg and Philip Fleckman
Dermatology Online Journal 7(1): 23F

The Jackson Laboratory, Bar Harbor, ME and the University of Washington, Seattle, WA.

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Human nails are relatively large and easy to evaluate clinically. The human nail is flattened dorsoventrally. Histologically the nail unit consists of a proximal nail fold, nail matrix, nail bed, and hyponychium. The mouse claw or nail superficially looks very different; it curves around the digit functionally slightly flattened laterally. However, at the histologic level the mouse nail is remarkably similar to the human nail, with all of the same structures. We developed simple methods to evaluate the very small nails of mice. These include evaluation and photography with a dissection microscope for large scale screening, processing the right front and rear feet for scanning electron microscopy after glutaraldehyde fixation, and processing the left feet for sagital histologic sectioning after formalin fixation. This approach provided methods for detailed evaluation, histology, and immunohistochemical studies. Screening inbred strains of mice and mutant mice from our Mouse Mutant Resource and Induced Mutant Resource, which are international repositories for mice, we found several models for onychogryphosis/onychoschisis (hairless and its alleles including rhino, slug null mutation, ichthyosis, lanceolate hair-J, and one of 8 models for alopecia areata), sensory deprivation syndrome (traumatic lesions associated with the nerve growth factor receptor null mutation), and longitudinal striations (flaky skin mutant mouse). Many others are under investigation and will yield important models that can be studied in detail longitudinally and manipulated to understand the mechanisms involved.

© 2001 Dermatology Online Journal