Scanning electron microscopy of corneal wound healing in the rabbit

Corneal lesions 7.5 mm. in diameter were made with an ocular trephine in rabbits. The time periods studied were 0, 30 min., and 1, 2, 4, 8, 16, and 24 hr. At the end of the time period, the cornea was flooded with 4% glutaraldehyde, buffered with cacodylate, pH 7.4, and kept moist until removed. It was then fixed for 24 hr. Half of the sample was dehydrated in graded alcohols, critical-point-dried, coated with gold palladium alloy, and viewed in an AMR-1000 scanning electron microscope at an accelerating voltage of 20 kv. From 0 to 4 hr. cell trauma, debris, and retraction are seen at the margin of the lesion. From 8 to 24 hr. a significant number of polymorphonuclear leukocytes are present over the total surface but in especially large numbers at the wound margin. At 16 to 24 hr. evidence of cell movement is present. Cells show ruffling membranes a decreased number of microvilli, and a few filopodia along the advancing edge.