Shimizu H, Ishiko A, Masunaga T, Kurihara Y, Sato M, Bruckner-Tuderman L, Nishikawa T
Department of Dermatology, Keio University School of Medicine, Tokyo, Japan.
Lab Invest. 1997 Jun;76(6):753-63.
Anchoring fibrils (AF) at the dermo-epidermal junction are well characterized as ultrastructural entities. They are composed mainly of collagen VII and play a key role in dermo-epidermal adhesion. Previous studies have suggested that AF originate in the lamina densa (LD), extend perpendicularly into the dermis, and insert into amorphous elements, called "anchoring plaques," in the dermal connective tissue. To elucidate the precise structural organization of the AF network in human skin, we analyzed quantitatively the distribution of different domains of collagen VII in the epidermal basement membrane zone, using various techniques of immunoelectron microscopy with a range of domain-specific antibodies that we prepared. Some electron-dense amorphous structures (ie, anchoring plaques) that were positive with aminoterminal end of collagen VII could be recognized only by pre-embedding en bloc labeling, and not by postembedding section labeling of immunoelectron microscopy. Quantitative analysis of surface labeling with postembedding immunoelectron microscopy demonstrated that most (> 90%) gold particles labeling the epitopes in the aminoterminal (NC-1 domain) of collagen VII were precisely localized to the LD, whereas no specific labeling was observed in the dermis. Most (> 90%) of the gold particles labeling the carboxyterminal end of collagen VII localized at a 160- to 360-nm distance from the LD, and most (> 90%) of the labeling epitopes in the central triple-helical collagenous domain were distributed between the LD and up to 360 nm from it; no specific labelings were observed beyond this area. These results suggest that most (> 90%), if not all, of the AF in human skin do not extend perpendicularly into the dermis, but instead originate and terminate in the LD, forming individual semicircular loops that constitute a network of AF.
真皮 - 表皮交界处的锚原纤维（AF）作为超微结构实体已得到充分表征。它们主要由Ⅶ型胶原蛋白组成，在真皮 - 表皮黏附中起关键作用。先前的研究表明，AF起源于致密层（LD），垂直延伸至真皮，并插入真皮结缔组织中称为“锚斑”的无定形成分中。为了阐明人类皮肤中AF网络的精确结构组织，我们使用一系列我们制备的结构域特异性抗体，通过各种免疫电子显微镜技术，定量分析了Ⅶ型胶原蛋白不同结构域在表皮基底膜带中的分布。一些对Ⅶ型胶原蛋白氨基末端呈阳性的电子致密无定形结构（即锚斑）只能通过包埋前整体标记识别，而不能通过免疫电子显微镜的包埋后切片标记识别。包埋后免疫电子显微镜表面标记的定量分析表明，大多数（>90%）标记Ⅶ型胶原蛋白氨基末端（NC - 1结构域）表位的金颗粒精确地定位于LD，而在真皮中未观察到特异性标记。大多数（>90%）标记Ⅶ型胶原蛋白羧基末端的金颗粒定位于距LD 160至360 nm处，并且中央三螺旋胶原结构域中的大多数（>90%）标记表位分布在LD及其360 nm范围内；在此区域之外未观察到特异性标记。这些结果表明，人类皮肤中大多数（>90%），如果不是全部的话，AF并非垂直延伸至真皮，而是起源并终止于LD，形成单个半圆形环，构成AF网络。
