Haftek M, Teillon M H, Schmitt D
INSERM U.346/CNRS, Human Skin and Immunity, E. Herriot Hospital, Lyon, France.
Microsc Res Tech. 1998 Nov 1;43(3):242-9. doi: 10.1002/(SICI)1097-0029(19981101)43:3<242::AID-JEMT6>3.0.CO;2-G.
The stratum corneum is composed of cornified keratinocytes, joined together with corneodesmosomes and embedded in the relatively hydrophobic intercellular substance. Formation of this horny layer and its constant desquamation are fundamental processes leading to the establishment of an efficient epidermal barrier. We examined structural changes occurring in the stratum corneum ex vivo, in order to better understand the mechanisms regulating corneocyte desquamation at the epidermal surface and influencing percutaneous penetration of exogenous substances. Morphologic modifications were induced by occlusion, increasing the tissue hydration, or by application of propylene glycol, a hydrophilic solvent of small molecular size. Distribution of the major epidermal antigens, markers of terminal differentiation, was studied immunohistochemically and showed no modification related to the tissue alteration. Skin samples were fixed in paraformaldehyde and either postfixed in OsO4 and embedded in Epon or postfixed in RuO4 and embedded in epoxy and acrylic resins. Structural composition and spatial organization of the elements present in the intercorneocyte spaces were evaluated ultrastructurally, with special attention paid to the fate of corneodesmosomes. Our results suggest that the spontaneous organization of lipids excreted into the intercellular spaces and constitution of the lamellar multilayers in the lower stratum corneum are at the origin of partition of the intercellular compartment to the hydrophobic and hydrophilic domains. The latter, compatible with the proteinic contents, seem to be displaced by the hydrophobic components undergoing reorganization, towards the invariable hydrophilic foci represented by corneodesmosomes. This mechanism may be involved in the delivery of proteolytic enzymes, thus contributing to the progressive degradation of corneodesmosomal proteins.
角质层由角质化的角质形成细胞组成，通过角质桥粒连接在一起，并嵌入相对疏水的细胞间物质中。这个角质层的形成及其持续的脱屑是建立有效表皮屏障的基本过程。我们研究了角质层在体外发生的结构变化，以便更好地理解调节表皮表面角质形成细胞脱屑以及影响外源性物质经皮渗透的机制。通过封闭增加组织水合作用，或应用丙二醇（一种小分子亲水性溶剂）来诱导形态学改变。通过免疫组织化学研究了主要表皮抗原（终末分化标志物）的分布，结果显示其与组织改变无关。皮肤样本用多聚甲醛固定，然后用四氧化锇后固定并包埋在环氧树脂中，或者用四氧化钌后固定并包埋在环氧和丙烯酸树脂中。超微结构评估了角质形成细胞间空间中存在的元素的结构组成和空间组织，特别关注角质桥粒的命运。我们的结果表明，分泌到细胞间空间的脂质的自发组织以及角质层下部板层多层结构的形成是细胞间区室划分为疏水和亲水区域的起源。后者与蛋白质成分相容，似乎被正在重组的疏水成分朝着由角质桥粒代表的不变的亲水焦点位移。这种机制可能参与了蛋白水解酶的传递，从而促进角质桥粒蛋白的逐步降解。
