EPITHELIAL WOUND-HEALING IN THE DENERVATED CORNEA

We studied the epithelial healing of denervated corneas in New Zealand albino rabbits with their left trigeminal ganglia surgically amputate d. On the 14th day after amputation, the corneas were keratectomized ( in 8.5 mm diameter) and documentation of the healing process began. We calculated the epithelial healing rate using simple regression analys is. We observed a mean healing rate of 0.463 +/- 0.059 mm(2)/hr (mean +/- SE) in the denervated corneas, compared to 0.609 +/- 0.031 mm(2)/h r in the control corneas; a statistically significant difference of P < 0.001. We performed scanning electron microscopic observation (SEM) at three points; before keratectomy, 48 hrs after keratectomy, and 14 days after keratectomy. SEM observation revealed that, in contrast to the control corneas, the surface of the epithelial cells in denervated corneas appeared rough with numerous exfoliating cells observed. This indicates that the epithelial cells might attach only weakly to the f loor in denervated corneas. Transmission electron microscopic observat ion (TEM) performed at 48 hrs and 14 days after keratectomy also suppo rts this finding. For example, the intercellular space is widened and fewer desmosomes are observed in denervated corneas. Using immunohisto chemistry, the surface of the wound bed was covered with fibronectin i n a similar fashion to the control. In the late stage, the denervated corneas demonstrated spontaneous epithelial breakdown with 83% of them having persistent epithelial defects. Epithelial healing in the contr ol corneas displayed no abnormal signs. On the 14th day after keratect omy, these eyes were enucleated for immunohistochemistry using bromode oxyuridine (Brd U) to observe dividing cells. The number of S-phase ce lls observed in meridional sections averaged 70.3 +/- 10.7 in the dene rvated corneas, compared to 29.1 +/- 2.30 in controls. We hypothesize that this increase in denervated corneas occurs in order to compensate for the excessive desquamation.