14周至足月胎儿角膜上皮干细胞的分布及超微结构观察

目的观察胚胎期角膜上皮干细胞的迁移规律及其超微结构,为利用胎儿角膜上皮干细胞提供理论依据。方法观察14至38周胎儿角膜上皮HE及抗人64ku角蛋白单克隆抗体(mAE5)染色反应,并观察胎儿角膜上皮干细胞的超微结构。结果14周角膜上皮由一层基底细胞被覆一至两层鳞状细胞构成,且仅有表层鳞状细胞mAE5弱阳性反应。17至29周缘部上皮有3~5层,中央部有2~3层,整层基底细胞mAE5反应阴性,其上鳞状细胞呈强阳性。33至38周角膜上皮已近成熟,仅剩缘部基底上皮细胞mAE5反应阴性。超微结构显示mAE5阴性反应的基底层细胞核异染色质多,胞质中细胞器较少,且细胞间连接也较少。结论胎儿角膜上皮干细胞呈现由全层向基底层,再向缘部逐渐迁移的分布规律,且超微结构较幼稚。

Localization and ultrastructure of corneal epithelial stem cells in human fetuses

Objective To evaluate the migrating regulation and ultrastructure of the corneal epithelial stem cells in human fetuses. Methods We examined the corneal cryosections of 14-38 weeks of gestation. Hematoxylin-eosin staining showed the stratified corneal epithelium and the corneal epithelial stem cells were localized by mouse monocolonal antibody against human 64-kilodalton keratin (mAE5), and the ultrastructure of the corneal epithelial stem cells was observed. Results At 14 weeks of gestation, the corneal epithelium was composed of a single basal cells layer and 1-2 superficial squamous cells layers. Some superficial squamous cells were mAE5 positive in the limbus as well as the central and peripheral cornea. At 17-29 weeks of gestation, the limbus epithelium developed from 3 to 5 cells layers and the central region from 2 to 3 cells layers. mAE5 positive cells were found in the suprabasal layers of all 3 regions examined but not in the basal layer. At 33-38 weeks of gestation, the corneal epithelium consisting of 4-6 cells layers was morphologically mature. mAE5 immunoreaction showed the negative cells were confined to limbus basal layer. The ultrastructure of basal layer cells showed they had more heterochromatin in the nucleus, less organells in the cytoplasm and less desmosomes among them. Conclusion The migration of corneal epithelial stem cells in the human fetuses was from the whole layers to basal layer and confined to limbus region finally, and their ultrastructure was immature.