Outer root sheath

Limat A, Breitkreutz D, Hunziker T, Klein CE, Nozer F, Fusenig NE Braathen LR (1994) Outer root sheath (ORS) cells organize into epidermoid cyst-like spheroids when cultured inside Matrigel a light-microscope and immunohistological comparison between human ORS cells and interfoUicular keratinocytes. Cell and Tissue Research 275 169-176. 

An in vitro method using hair follicle cells to investigate unscheduled DNA synthesis (UDS) has been developed. Plucked follicles were exposed to tritiated thymidine and the UDS activities were determined autoradiographically (the number of dark grains in the outer root sheath of nonperipheral cells were used to estimate UDS). Many, but not all chemicals that have been shown to induce UDS in rat liver cells also stimulated UDS in hair follicles. 

Autologous keratinocytes and fibroblasts have generally been derived from biopsies of the patient s uninjured skin [71 73]. Recently, keratinocytes have been isolated from the outer root sheath of plucked hair follicles [41,42]. The cells can be expanded in culture and used to populate skin substitutes in vitro. Grafted as epithelial sheets or as composites of biopolymers and cells, these are theoretically permanent skin substitutes once engraffment is achieved [25-27,33,41]. 

Limat, A., Mauri, D., and Hunzifcer, T., Successful treatment of chronic leg ulcers with epidermal equivalents generated from cultured autologous outer root sheath cells, J. Invest. Dermatol, 107, 128,1996. 

The innermost layer, next to the hair root, is the internal epithelial root sheath, which is composed of three layers (1) internal root sheath cuticle, (2) middle granular epithelial layer (Huxley s layer), and (3) outer pale epithelial layer (Henle s... 

Anagen is followed by a brief involutional phase called catagen. Here the follicular cells cease division and the hair root shrivels to a small group of cells ascending toward the surface, pushing the inert hair shaft ahead of it. Another characteristic feature in catagen is the phenomenon of cell death by apoptosis. Apoptosis is observed in the outer sheath cells at the level of the bulb and of the epithelial column. 

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