Banks-Schlegel S, Green H
J Cell Biol. 1981 Sep;90(3):732-7. doi: 10.1083/jcb.90.3.732.
Different stratified squamous epithelia, whether they bear a stratum corneum or not, are shown by immunofluorescence to possess the precursor protein of the cross-linked envelope that is characteristic of epidermal s. corneum. This protein, involucrin, is not present in the deepest epithelial cells but appears in the course of their outward migration. The boundary at which involucrin first appears can sometimes by correlated with a visible boundary between zones of large and small cells. Cultured keratinocytes, derived from all stratified squamous epithelia (epidermal, corneal, conjuctival, esophageal, lingual, and vaginal), form colonies that grow together to form a stratified epithelium. The cells of the basal layer are nearly always free of detectable involucrin, but, in contrast to the natural epithelium, this protein usually makes its appearance in the cells immediately above the basal layer. When a cultured epithelium derived from epidermal keratinocytes is detached and applied as a graft to animals, the cells flatten and the distinctness of the basal layer is at first reduced; but with time the organization of the epithelium becomes more characteristic of epidermis. Cell size and shape become more orderly along the cell migration pathway, and involucrin first appears at some distance from the basal layer, instead of in immediately suprabasal cells, as in the cultured epithelium. The progeny of dissociated and cultured keratinocytes are therefore able, when grafted, to reassemble an epidermis in which the timing of specific gene expression is restored to that of the original tissue.
不同的复层鳞状上皮，无论有无角质层，经免疫荧光显示都具有交联包膜的前体蛋白，这是表皮角质层的特征。这种蛋白即内披蛋白，不存在于最深层的上皮细胞中，而是在细胞向外迁移过程中出现。内披蛋白首次出现的边界有时可与大小细胞区域之间的可见边界相关联。源自所有复层鳞状上皮（表皮、角膜、结膜、食管、舌和阴道）的培养角质形成细胞形成菌落，这些菌落生长融合形成复层上皮。基底层细胞几乎总是检测不到内披蛋白，但与天然上皮不同的是，这种蛋白通常在紧邻基底层的细胞中出现。当源自表皮角质形成细胞的培养上皮分离后作为移植物应用于动物时，细胞会变扁平，基底层的清晰度起初会降低；但随着时间推移，上皮组织会变得更具表皮特征。沿着细胞迁移途径，细胞大小和形状变得更加规则，内披蛋白首先出现在距基底层一定距离处，而不像在培养上皮中那样出现在紧邻基底层上方的细胞中。因此，解离并培养的角质形成细胞的后代在移植时能够重新组装成表皮，其中特定基因表达的时间恢复到原始组织的水平。
