Fujisawa K, Kushida T
Department of Anatomy, Tokyo Women's Medical College, Japan.
Kaibogaku Zasshi. 1995 Dec;70(6):521-40.
Hair follicles of male Wistar rats in the anagen stage were examined by light and electron microscopy. A distinct monocellular layer was identified between the Henle's layer and the outer root sheath (ORS). In the lower part of the ORS, this cell layer is more closely bound to the inner root sheath (IRS) than to the ORS, while in the upper half the situation is reversed. Electron density and staining property of this layer are gradually changed according to regions of the hair follicle which may indicate the metabolic conditions of the organism. The origin of this layer can be traced back to the germinal matrix directly facing the neck of the hair papilla. Findings are also reported about the gaps formed between the cells of Henle's layer after keratinization and about the contact formed between the cells of Huxley's layer and the cells of this monocellular layer through these gaps. Our observation reported in this study strongly suggests that this layer belongs neither to the IRS nor to the ORS, but that it represents an independent layer of cells. Therefore we propose to name this layer the "middle root sheath." This middle root sheath may serve the following three functions: 1) alleviation of intrinsic friction generated by colliding cell dynamics between the IRS and the ORS, 2) deterrence of keratinization of the ORS after exfoliation of the IRS and 3) secretion and excretion of metabolites.
对处于生长期的雄性Wistar大鼠毛囊进行了光镜和电镜检查。在亨勒层和外根鞘(ORS)之间发现了一个明显的单细胞层。在ORS的下部,该细胞层与内根鞘(IRS)的结合比与ORS更紧密,而在上半部分情况则相反。该层的电子密度和染色特性根据毛囊区域逐渐变化,这可能表明生物体的代谢状况。该层的起源可直接追溯到面对毛乳头颈部的生发基质。还报告了关于亨勒层细胞角质化后形成的间隙以及赫胥黎层细胞与该单细胞层细胞通过这些间隙形成的接触的发现。本研究报告的观察结果强烈表明,该层既不属于IRS也不属于ORS,而是代表一个独立的细胞层。因此,我们建议将该层命名为“中根鞘”。这个中根鞘可能具有以下三个功能:1)减轻IRS和ORS之间细胞动态碰撞产生的内在摩擦,2)在IRS脱落后抑制ORS的角质化,3)代谢物的分泌和排泄。