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Morphological and morphometrical study on the dorsal skin of Wistar
and WBN/ILA-Ht rats in their developing stage. Evaluation of the
proliferation and apoptotic processes
S. Iwamoto, H. Nakayama and K. Doi
Department of Veterinary Pathology, Faculty of Agriculture,
The University of Tokyo, Bunkyo-ku, Tokyo, Japan
Offprint requests to: Shoko
Iwamoto, Department of Veterinary Pathology, Faculty of Agriculture, The
University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113, Japan
Summary. The detailed histology
of the dorsal skin of Wistar-derived hypotrichotic WBN/ILA-Ht rats
(HtRs) was examined in their developing stage (at 3 and 7 weeks of age)
using Wistar rats (WRs) as controls. As a result, except for the existence
of time-lag in the hair follicular cycle and some quantitative differences,
there were no essential qualitative differences between the two strains.
The follicular epithelial cell number and the amounts of tonofilaments and
trichohyalin granules were less in HtRs than in WRs in the same phase of
hair follicular cycle. In addition, the diameter of hair shaft was significantly
larger in WRs than in HtRs at 7 weeks of age. The number of proliferating
cell nuclear antigen (PCNA)-positive epidermal basal cells decreased in
HtRs and increased in WRs from 3 to 7 weeks of age, respectively. Apoptosis
was sparsely observed in the sebaceous gland epithelial cells, keratinizing
portion of hair cuticules and inner root sheath in both strains, but the
frequency of apoptosis in the hair follicle was somewhat higher in 7-week-old
HtRs. HtRs are considered to be useful experimental animals for dermatotoxicological
studies. Histol. Histopathol. 13, 981-988 (1998)
Key words: WBN/ILA-Ht
rat, dorsal skin, morphology, hypotrichosis, TUNEL, PCNA
DOI: 10.14670/HH-13.981
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