Quantitative analysis of epithelial changes during wound healing in palatal mucosa of guinea pigs

The epithelium of wounded guinea pig palate was subjected to stereologic analysis. A total of 18 biopsies (animals) were used. Biopsies were taken at 18, 48, 96 and 120 h after wounding. Point counting procedures were employed to analyse electron micrographs sampled from one (18 h) or two epithelial strata (48, 96 and 120 h). The essential modulations in epithelial structure as wound healing proceeds were as follows: During the early phases characterized by formation and advancement of epithelial lips (18 and 48 h), migrating cells converged towards a cell type which structurally was less differentiated than normal basal cells. This alteration was expressed by a decrease in volume density of cytoplasmic organelles, mainly mitochondria, free ribosomes and tonofilament bundles, coupled with an increase in volume density of lysosomal bodies. Concomitantly, the volume density of cytoplasmic ground substance rose markedly. Subequent to fusion of contralateral migratory lips (96 and 120 h) reversion to normal epithelial structure was indicated by the increment in magnitude of basal cell parameters. Further structural density gradients from basal towards upper cell layers appeared. This pattern was mainly displayed by mitochondria, free ribosomes, and tonofilament bundles. The magnitude and gradation of most tissue and cell parameters were not yet re-established at 120 h. The density of tonofilament bundles and the density level of cytoplasmic ground substance in particular deviated.