Ultrastructural changes of subepithelial capillaries following graft epithelialization.

This study investigated architectural changes in the nourishment-providing capillaries beneath the epithelium that accompany graft epithelialization. A total of 77 mongrel dogs underwent free gingival autografts involving the maxillary canine and its attached gingiva. Comparative investigations relating the architectural transformations and endothelial permeability of the capillaries were made histopathologically, with graft epithelialization as an indicator. Microscopic findings revealed that the subepithelial capillaries transformed from loop structure into glomus-like structures. The endothelium changed ultrastructurally from the continuous type to the fenestrated. This occurred during the most active graft epithelialization phase. By the time the epithelium of the graft had matured, the fenestrated microvascular structure reverted to the continuous type and changed from a glomus-like structure to a network capillary system. However, by the 84th postoperative day, the subepithelial capillaries, still exhibiting network structure, had not yet returned to the loop structure indigenous to the gingiva. Observations indicated that transformation of the structure of the nourishment-providing capillaries was attendant to and simultaneous with the changes brought about by graft epithelialization.