Zagon I S, Sassani J W, Ruth T B, McLaughlin P J
Department of Neuroscience and Anatomy, The Milton S. Hershey Medical Center, The Pennsylvania State University, College of Medicine, 500 University Drive, Hershey, PA 17033, USA.
Brain Res. 2000 Nov 3;882(1-2):169-79. doi: 10.1016/s0006-8993(00)02864-x.
The number and distribution of mitotic epithelial cells in the ocular surface during homeostasis and in response to abrasion of the mammalian cornea were determined. Normal rats and those receiving a 3 mm diameter centrally located epithelial defect, received an intraperitoneal injection of colchicine 6 h prior to sacrifice. Mitosis in the basal epithelium during homeostasis was comparable in magnitude across the ocular surface epithelium, with the exception of a few mitotic figures in the midline. Thirty percent of the mitotic figures were in the basal layer (layer 1), and 70% were in layer 2; the cells in layer 2 were often noted to retain connection to the basal lamina by cytoplasmic stalks. Mitosis was rarely noted in the regenerating epithelium. However, summation of M phase cells in both the basal and suprabasal epithelium adjacent to the wound showed increases of 3- and 5-fold at 30 and 36 h after abrasion, respectively, from levels at homeostasis and the time of injury. In striking contrast to homeostatic epithelium, 80% of the mitotic cells were located in layer 1 of the corneal epithelium, with normal distribution observed by 72 h. Mitosis in the limbus and conjunctiva was increased 3-fold at 30 h and 24 h, respectively, from values at homeostasis and the time of debridement. These results, using rigorous statistical analysis and precise topographic assessment, showed that mitosis is not impeded - but rather often accelerated - following denuding of the corneal epithelium and that the spatial distribution of mitotic cells is correlated with wounding. The data revealed that re-epithelialization of the corneal epithelium is not dependent on mitosis in the regenerating epithelium, but rather in the adjacent unwounded epithelium of the cornea, with most cells being located in the basal layer until re-epithelialization is completed. Mitotic cells in the limbus and conjunctiva may be related to replenishment of ocular surface epithelial cells used in the repair process rather than directly supplying the abraded surface.
确定了哺乳动物角膜在稳态及角膜擦伤时眼表有丝分裂上皮细胞的数量和分布。正常大鼠以及接受直径3毫米中央上皮缺损的大鼠，在处死前6小时腹腔注射秋水仙碱。稳态时，除中线处有少数有丝分裂象外，整个眼表上皮基底上皮中的有丝分裂在数量上相当。30%的有丝分裂象位于基底层（第1层），70%位于第2层；常可见第2层细胞通过细胞质柄与基底膜保持连接。在再生上皮中很少见到有丝分裂。然而，擦伤后30小时和36小时，伤口附近基底和基底上层上皮中M期细胞的总和分别比稳态时和损伤时增加了3倍和5倍。与稳态上皮形成鲜明对比的是，80%的有丝分裂细胞位于角膜上皮的第1层，72小时时观察到分布正常。角膜缘和结膜中的有丝分裂分别在30小时和24小时时比稳态时和清创时的值增加了3倍。这些结果通过严格的统计分析和精确的地形评估表明，角膜上皮剥脱后有丝分裂并未受到阻碍，反而常常加速，且有丝分裂细胞的空间分布与创伤相关。数据显示，角膜上皮的再上皮化不依赖于再生上皮中的有丝分裂，而是依赖于角膜相邻未受伤上皮中的有丝分裂，在再上皮化完成之前，大多数细胞位于基底层。角膜缘和结膜中的有丝分裂细胞可能与修复过程中使用的眼表上皮细胞的补充有关，而不是直接供应擦伤表面。
