Van Neste Dominique, Leroy Thérèse, Conil Séverine
Skinterface, Tournai, Belgium.
Skin Res Technol. 2007 Nov;13(4):436-43. doi: 10.1111/j.1600-0846.2007.00248.x.
BACKGROUND/AIM: Classically, the hair cycle is described as a sequence of three successive phases: a hair-growth phase named anagen, a regression phase or catagen and a resting phase or telogen. In rodents, it appears that the resting hair follicle population contains also a new phase that has been identified recently as the exogen phase of the hair cycle. This phase leads to the release of the telogen club and results in hair shedding. The aim of this paper is to propose a method that is applicable to humans and that is able to discriminate the two components of the resting hair population i.e. the telogen and the exogen hair follicles.
We used non-invasive approaches to entrap exogen scalp hair into silicon-based polymers. We also extracted growing and non-growing hair with a calibrated dynamometer. We characterized differences between anagen, catagen, telogen and exogen root ends with histochemical stains and with the scanning electron microscope. Furthermore, we documented all known hair-cycle stages with the contrast-enhanced phototrichogram (CE-PTG) technique.
We demonstrated that anagen and telogen hair are firmly anchored to the hair follicle and that cohesion forces are correlated with hair thickness. On the contrary, exogen hair are passively retained within the hair follicle. Among the resting hair population, telogen clubs retain cellular elements of the outer root sheaths that are not found on exogen hair. The specificity of the new exogen collection method was documented with the simultaneous use of the CE-PTG method: indeed anagen, catagen and telogen follicles remain unaffected by the exogen extraction procedure.
Exogen hair can be sampled specifically from the human scalp with a new non-invasive method. Our data suggest that the casual levels of exogen hair, in normal individuals and under the present experimental conditions, are usually less than seven hair per cm(2).
背景/目的：传统上，毛发周期被描述为三个连续阶段的序列：生长期，称为生长期；退行期或退行期；休止期或休止期。在啮齿动物中，休止毛囊群体似乎还包含一个新阶段，最近被确定为毛发周期的外生期。这个阶段导致休止期毛球的释放并导致毛发脱落。本文的目的是提出一种适用于人类的方法，该方法能够区分休止毛发群体的两个组成部分，即休止期和外生期毛囊。
我们使用非侵入性方法将外生头皮毛发捕获到硅基聚合物中。我们还使用校准的测力计提取生长和不生长的毛发。我们用组织化学染色和扫描电子显微镜表征生长期、退行期、休止期和外生期根端之间的差异。此外，我们用对比增强光毛发生图（CE-PTG）技术记录了所有已知的毛发周期阶段。
我们证明生长期和休止期毛发牢固地锚定在毛囊上，内聚力与毛发厚度相关。相反，外生期毛发被动地保留在毛囊内。在休止毛发群体中，休止期毛球保留了外生期毛发上未发现的外根鞘细胞成分。同时使用CE-PTG方法证明了新的外生期收集方法的特异性：事实上，生长期、退行期和休止期毛囊不受外生期提取程序的影响。
可以用一种新的非侵入性方法从人类头皮中特异性采集外生期毛发。我们的数据表明，在正常个体和当前实验条件下，外生期毛发的偶然水平通常低于每平方厘米7根毛发。
