Dubin-Johnson综合征肝细胞色素和脂褐素的超微结构特征

Ultrastructural characteristics of pigment and lipofusin in hepatocytes of Dubin-Johnson syndrome

目的研究Dubin—Johnson综合征肝细胞色素的超微结构特征，为Dubin—Johnson综合征的诊断和鉴别诊断提供新的方法。方法按电镜常规进行标本制备，应用透射电镜对18例Dubin—Johnson综合征患者肝穿刺活检组织进行超微结构观察。结果半薄切片甲苯胺蓝染色发现，肝细胞内有明显的色素沉积，主要见于肝细胞毛细胆管周围。超薄切片，铀、铅染色后发现肝细胞内有特征性的单层膜包裹颗粒。圆形或卵圆形，大小为0．2～1．0μm。颗粒大多聚集于毛细胆管周围区域的肝细胞内，也可散在分布于肝细胞质内。这些颗粒缺少典型脂褐素颗粒的分叶结构。呈多形性，电子密度不一。常存在许多与脂滴相关非常致密的小体，而溶酶体的其余部分由中等电子密度的均一性颗粒物组成，表现为点彩状外观。与脂褐素相比，它们相对富含颗粒状基质，而脂滴样结构少见。这些颗粒可互相融合，形成更大的不规则结构。肝小叶中央区可发现大量无定形颗粒，这些颗粒缺少脂滴样结构。相反，在肝小叶周围的肝细胞内电子致密小体丰富。在某些方面，它们类似脂褐素，但与脂褐素不同的是，某些颗粒内含有明显的致密核心结构。结论特征性的含致密核心结构的溶酶体对Dubin—Johnson综合征的诊断有重要的参考价值。

Objective To investigate the uhrastructural characteristics of pigment and lipofusin in hepatocytes of Du- bin-Johnson syndrome and provide a new method for diagnosis and differential diagnosis of Dubin-Johnson syndrome. Methods The liver biopsy specimens were obtained from 18 patients with Dubin-Johnson syndrome and processed by routine transmission electron microscopy. Results Toluidine blue staining of semi-thin sections detected numerous pig- ment granules in pericanalicular areas of hepatocytes. The ultra-thin sections were stained with uranyl acetate and lead citrate, a specific membrane-bounded particles were found in hepatocytes. The particles were round or oval, the size was 0.2 pom to 1.0 Ixm. Most of these particles localized in pericanalicular areas or sparsed in the hepatocytes. They lack the lobulation typical of lipofusin granules,they were pleomorphic and of variable electron desity. A number of very dense bodies, frequently associated with lipid droplets, were present while remainder of the particles was made up of moderately electron dense homogenous granular particles having a finely stippled appearance. Compared with lipo- fusin granules, they riched in granular matrix and less lipid droplets. These particles could fuse each other into a larger irregular structure. A number of amorphous granules were found in the central zone of liver lobu｜e, lipid droplets were absent in these granules. The electron dense bodies were evident in the hepatocytes of the periphery of liver lobule, they were similar to lipofusin in some features but they contained dense-core structure. Conclusion The specific lyso- somes containing electron dense-core structure in hepatocytes is helpful for diagnosis of Dubin-Johnson syndrome.