1993 年 26 巻 5 号 p. 381-389
In situ hybridization histochemistry with the use of a digoxigenin-labeled ribonucleotide probe for basic fibroblast growth factor (bFGF) mRNA demonstrated bFGF transcripts in the masseter muscle of dystrophic (mdx) mouse and in vibrissae and small hair follicle of the rat peri-oral skin. A conspicuous hybridization signal was detected in the central part of the cytoplasm of the smallest myoblasts in the process of initial regeneration or differentiation. bFGF mRNA staining decreased in intensity as the myoblasts increased in size due to the production of myofilaments. Endomysial fibroblasts and extracellular matrix did not exhibit any detectable bFGF mRNA expression. In transverse sections of the hair follicles and vibrissae, a bFGF mRNA positive reaction was noted in the central portion of individual follicles, which were endowed with a non-hybridized core of variable diameter. The hybridization signal in longituidinal sections of hair follicles was localized mainly to keratinizing hair cortical cells; the matrix was scarcely labeled with the probe. The dermal papillae of hair follicles were devoid of bFGF mRNA staining. These findings suggest that early regenerating or differentiating myoblasts produce bFGF, rather than internalizing the growth factor originating in other tissues and that part of bFGF generated in the hair cortical cells is conveyed to the hair matrix and external root sheath which has been shown, by immunohistochemistry, to contain bFGF-like substances.
