Actin bundles in human hair follicles as revealed by confocal laser microscopy |
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Authors: | Minao Furumura Harunori Ishikawa |
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Institution: | (1) Department of Anatomy, Gunma University School of Medicine, Maebashi, Gunma 371, Japan, JP |
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Abstract: | A confocal laser microscope was used to examine the distribution pattern of actin bundles in whole-mounts of human hair follicles
stained with fluorescently labeled phalloidin. Actin bundles were found exclusively in the epithelial outer root sheath of
the lower and middle portions of the follicle. In the growth stage, the lower follicle was characterized by well-developed
actin bundles arranged circumferentially in the innermost and outermost cell layers of the outer root sheath. Actin bundles
in the innermost cells were aligned end-to-end so that they formed complete circular bands surrounding the inner root sheath.
In the outermost cells, actin bundles ran underneath the basal plasma membrane to which they attached at both ends. In contrast,
in the quiescent stage, actin bundles in the lower follicle were disposed radially toward the follicle surface where they
terminated perpendicular to the basal plasma membrane. In the middle follicle, circumferential actin bundles were found only
in the intermediate layer of the outer root sheath throughout the hair cycle. Immunofluorescent anti-myosin and anti-α-actinin
staining showed a striated pattern along actin bundles. Vinculin was localized at both ends of actin bundles, corresponding
to the cell-to-cell or cell-to-substrate adherens junctions. Glycerinated follicles changed in shape on the addition of MgATP,
suggesting a contraction of actin bundles. From these observations, we conclude that actin bundles in the hair follicle are
comparable to stress fibers and that they serve as a tensile scaffold for the growth and integrity of the follicle.
Received: 6 May 1995 / Accepted: 25 October 1995 |
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Keywords: | : Actin Microfilaments Stress fibers Epithelium Hair follicle Human |
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