Figure 2: Centripetal migration of the corneal epithelium is retained with greater dispersal when replicative potential increases.

Representative simulations of corneal epithelium in which TAC(max), the maximal number of symmetric cell divisions in the basal layer after production of the TACs by the LESCs, was either 2 (a,d,g), 3 (b,e,h) or 4 (c,f,i). (a–c) Generation maps at t=1,000 for each scenario. In each map, the LESCs are black cells circumscribing the cornea and the TACs that have reached their replicative limit are depicted in red. Cells with 1, 2, 3 or 4 symmetric cell divisions remaining are colour-coded according to the key at right. Cells throughout the cornea can give rise to suprabasal terminally differentiating cells, which are not shown. (d–f) Radial distribution of replicative potential within the corneal epithelium. Kernel density plots as a function of distance from the centre of the cornea are shown for each TAC(max) estimated from 25 simulations. The kernel density is an estimation of the underlying probability distribution for each cell category. The colours for the plots correspond to those in the generation maps in a–c. (g–i) The clonal lineage maps corresponding to the generation maps in a–c. (j) Increased spread of TACs away from ideal centripetal migration with increasing replication potential. The LDs were calculated for cells in corneas at t=750 in which the TAC(max) was either 2, 3 or 4. The mean±s.d. of the LDs are shown for 25 simulations of each case. The LDs of all three TAC(max) were different by one-way ANOVA with Tukey’s multiple comparisons correction at a P<0.0001.