Experimental studies by the resin-casting method on the vascular structure of the colon following stapler anastomoses.

A Russian stapler and an EEA stapler were used for end-to-end anastomosis of the canine descending colon. The vascular structures of the anastomotic sites were investigated for postoperative changes at two, three, four, five, and six weeks after anastomosis by using the resin-casting method, with a scanning electron microscope. The two techniques of anastomotic stapling led to the following differences: at two weeks or more following anastomosis, it was found that, compared with the EEA stapler, the site stapled with the Russian device showed a slightly more markedly irregular microvascular pattern of the capillary network in the mucosal membranes along the anastomotic suture line and what were believed to be microulcerations as well. Samples of the Russian stapler at two and three weeks postoperatively showed that the fault zones had developed in the vascular casts of the mucosal capillary system between the area of irregular vasculature and the normal mucosa. It was clearly established, however, that the microvascular channels in the mucosal membrane of the anastomotic site across the orad and anad segments of the colon had already formed after two weeks with both of the stapling techniques. New microvessels grew within a range of about 10 mu in diameter from the cut-off surface of the mucosa and united. No necrotic destruction of tissue or deficiency findings had manifested themselves in the inverted cuff zone of the anastomotic site, and the staple had been enveloped by the blood vessels of the submucosal layer and embedded in the intestinal wall during the period of two to six weeks. New microvessels, 10 to 15 mu in diameter, were found to have already formed in the two-week samples, passing vertically across the lumen of the closed eye of the staple, and no differences in vascular structure were detected, depending on the different shapes of staples used. Five to six weeks after the anastomotic surgery, the mucosal membranes in the anastomotic site showed a normal vascular structure with only minute residual indentations.