Kobayashi H, Tagami H
Department of Dermatology, Tohoku University School of Medicine, 1-1 Seiryo-machi, Aobaku, Sendai 980-8574, Japan.
Br J Dermatol. 2004 Mar;150(3):563-7. doi: 10.1046/j.1365-2133.2003.05741.x.
The vermilion border of the lips (lip for short) is the only part on the face where the oral mucosa is persistently exposed to the outside. Despite its prominent presence on the face, constituting not only the target of cosmetics but also the site for various skin diseases, its functional properties remain almost unknown.
To elucidate the functional properties of the vermilion border of the lips.
We studied the biophysical properties of the lip by comparing them with those of the cheek skin in 303 healthy Japanese females aged 21-80 years, in winter. We used a closed-chamber system to measure transepithelial water loss (TEWL) of the lip to avoid the effect of breathing. Moreover, we examined the effects of oral etretinate, a drug that definitely produces dry, scaly lips, on the lips of seven male patients aged 49-89 (average 67) years.
TEWL was significantly almost three times as high on the lips as that on the cheek which is a site that shows far higher levels than do other body areas. TEWL decreased with age more remarkably on the lip than on the cheek. High-frequency conductance, a parameter for surface hydration state, was significantly lower on the lip than on the cheek. The mean values obtained were about one-third of those on the cheek, and no age-related changes were observed either on the lip or on the cheek. The superficial epithelial cells on the lip were parakeratotic and larger than those of the cheek skin. Furthermore, we detected a significant increase in TEWL on the lip as well as on the cheek of patients treated with oral etretinate.
It appears that the incomplete corneocyte formation of the lip surface is responsible for the poor barrier function and water-holding capacity.
唇部的朱红色边缘（简称唇）是面部唯一持续暴露于外界的口腔黏膜部位。尽管其在面部十分显眼，不仅是化妆品的作用对象，也是各种皮肤病的发病部位，但其功能特性几乎仍不为人知。
阐明唇部朱红色边缘的功能特性。
我们在冬季对303名年龄在21至80岁之间的健康日本女性进行研究，通过比较唇部与脸颊皮肤的生物物理特性来研究唇部。我们使用密闭腔室系统测量唇部的经皮水分流失（TEWL），以避免呼吸的影响。此外，我们还研究了口服阿维A对7名年龄在49至89岁（平均67岁）男性患者唇部的影响，该药物肯定会导致唇部干燥、脱屑。
唇部的TEWL几乎显著高于脸颊，而脸颊部位的TEWL已远高于身体其他部位。唇部的TEWL随年龄下降的幅度比脸颊更显著。高频电导作为表面水合状态的一个参数，在唇部显著低于脸颊。唇部的测量平均值约为脸颊的三分之一，且在唇部和脸颊均未观察到与年龄相关的变化。唇部的浅表上皮细胞为不全角化，且比脸颊皮肤的细胞更大。此外，我们发现口服阿维A治疗的患者唇部和脸颊的TEWL均显著增加。
唇部表面角质形成细胞形成不完全似乎是其屏障功能和保水能力较差的原因。
