Abstract
There have been many hypothesis on the process of recirculation, certainly the essential factor for a graft “take” (1) One theory claims that recirculation starts with the anastomosis of a graft and the vessels of the graft bed; (2) There is the hypothesis that recirculation starts with the penetration of a graft by newly-formed vessels sprouting from the recipient bed; (3) Then there is the hypothesis which explains that recirculation starts by the combination of processes (1) and (2). In this study, the process of recirculaton in 28 adult mongrel dogs, which were subjected to free gingival autograft, was observed. Specimens of vascular corrosion casts on the 1st, 2nd, 3rd, and 5th day after grafting were examined under a scanning electron microscope. At the same time, investigations into pathohistology and ultrast ructure were made for comparative studies as well as to develop a theory concerning three-dimensional vascular architecture.
On the postoperative 3rd day, the results of resin injections indicated that vascular structure developed 3/4 area of the graft from the edges. On the postoperative 5th day, the injection was observed to be all over the graft, reaching the capillaries under the epithelium. Basically, the construction of the capillaries were almost identical to the loop construction indigenous to the gingiva.
At the graft-bed junctions, existing vessels of the graft communicated with vessels in the recipient bed with newly-formed sinusoidal vessels. These new vessels still retained mesenchymal characteristics, being formed by the multidimensional differentiation of undifferentiated mesenchymal cells into the pericyte of the endothelium. In the existing vessels of the graft and the vessels in the recipient bed, as well neither mitosis, migration nor wandering of the endothelial cells were observed. This served to indicate that recirculation to the graft is completed through the newly-formed sinusoidal vessels.
