Effect of Aging on the Structure and Sebum of Human Sebaceous Glands ; Morphological and Biochemical Study

为了阐明人体皮脂腺功能随年龄的变化，采用计算机立体成像和电子显微镜对不同年龄的正常人前额皮脂腺进行了检查，并对其前额皮脂样品进行了生化分析。使用计算机图形分析系统（Cosmozone 2SA, Nikon, Tokyo）对皮脂腺进行三维分析。在女性中，10岁以下的受试者皮脂腺体积较小，20多岁时体积最大，50多岁后体积变小。男性虽然也在20多岁时达到最大值，但一直保持到40多岁或50多岁，60多岁开始减少。皮脂腺平均体积越大，标准差值越大。大皮脂腺立体显示球囊样肿胀。皮脂腺体积的增加是由于皮脂细胞数量和大小的增加。在超微结构上，青壮年大皮脂腺的外周皮脂细胞呈长方体状，成熟皮脂细胞有大量大小相近的脂滴，而儿童和老年人小皮脂腺的外周皮脂细胞呈扁平状，成熟皮脂细胞有大小不一的脂滴。这些形态学和形态计量学数据表明，尽管在中年个体中皮脂腺的大小在两性之间存在差异，但两性皮脂腺存在明显的年龄相关结构变化。用吸收法从不同年龄的正常人额头皮肤上获得皮脂样本。在20多岁之前，男性和女性的皮脂量都在迅速增加。女性在40岁后逐渐下降，而男性在40岁后保持较高水平。用薄层色谱法测定了油脂样品中蜡酯/[胆固醇+胆固醇酯]（WE/[C+CE]）的比值，这是一个很好的表达皮脂腺活性的指标。与年龄相关的比率变化与女性皮脂量的变化相似，但在男性中则不同。40岁以后，男性的这一比例与女性相似，呈下降趋势，尽管男性的这一比例高于女性。从皮脂样品中提取WE馏分，采用熔融石英毛细管柱气液色谱法分析其脂肪酸甲酯。男女WE中C_<16:1>的百分比也表现出年龄相关的变化，与WE/[C+CE]比值相对应。从所有个体的24小时尿液样本中分离尿雄激素，三甲基硅化并提交气液色谱分析。睾酮水平与男女皮脂中WE/[C+CE]比值和C_<16:1>直链脂肪酸比值呈正相关。在女性中，17-酮类固醇的量也显示出与这些皮脂指数呈正相关，但在男性中，除了婴儿期外，没有显示出这种相关性。男性皮脂腺的活动似乎主要受睾酮作为内在因素的控制，而女性皮脂腺似乎对肾上腺雄激素比男性更敏感。这些形态学和生化的发现可能表明，人类皮脂腺在两性中表现出明显的与年龄相关的结构和功能变化，尽管两性之间的变化模式存在一些差异，特别是在中世纪。少

To elucidate the changes of human sebaceous gland function with aging, forehead sebaceous glands of normal individuals of various ages were examined by computer-stereography and electron microscopy, and their forehead sebum samples were biochemically analyzed. The three-dimensional analysis of sebaceous glands using a computer graphic analysis system (Cosmozone 2SA, Nikon, Tokyo) was performed. In females, the volumes of sebaceous glands were small in subjects of less than 10 years of age, the largest at 20s and became smaller after 50s. In males, although they also reached the maximum at 20s,they maintained the large sizes until 40s or 50s and began to decrease at 60s. The larger average volumes of sebaceous glands showed the larger standard deviation values. The large sebaceous glands stereographically revealed balloon-like swelling. The increase in volume of sebaceous gland was due to increases in both number and size of sebocytes. Ultrastructurally, in the large sebaceous glands of … More young adults the peripheral sebocytes were cuboid in shape and the mature sebocytes had a large number of lipid droplets of a similar size, whereas in the small ones of children and aged persons the peripheral sebocytes were flat in shape and the mature sebocytes had lipid droplets of various sizes. These morphological and morphometrical data suggest that there are distinct age-related structural changes of human sebaceous glands in both sexes, although there is a difference in their size between the sexes in middle-aged individuals. Sebum samples were obtained from the forehead skin of normal human individuals of various ages by an absorption method. The amount of sebum rapidly increased until 20s in both sexes. It gradually decreased after 40s in females, whereas it was maintained at a high level after 40s in males. Wax esters/[cholesterol + cholesterol esters] (WE/[C+CE]) rations, which may be a good index to express the sebaceous gland activities, in the sebum samples, were measured by thin-layer chromatography. The age-related change of the ratios was similar to that of sebum amounts in females, but it was not in males. The ratios in males decreased after 40s similarly to those in females, although they kept higher levels in males than females. The WE fractions were extracted from the sebum samples and their fatty acid methyl esters were analyzed by gas-liquid chromatography using fused-silica capillary column. The percentages of C_<16:1> in WE also showed age-related changes, corresponding to those of WE/[C+CE] ratios, in both sexes. Urinary androgens were separated from 24 hrs-urine samples of all the individuals, trimethylsilylated and submitted to analysis by gas-liquid chromatography. The amounts of testosterone showed age-related changes positively correlated with those of either WE/[C+CE] ratios or C_<16:1> straight chain fatty acid proportions in sebum in both sexes. The amount of 17-ketosteroid also revealed a positive correlation with these sebum indices in females, but in males it did not show such a correlation except for infancy period. The activity of male sebaceous glands seemed to be controlled principally by testosterone as an intrinsic factor, whereas the female sebaceous glands seemed to be more sensitive to adrenal androgens than male ones. These morphological and biochemical findings may indicate that human sebaceous glands show distinct age-related changes of structures and functions in both sexes, although there are some differences in the patterns of the changes between the sexes especially in middle ages. Less