Comparative healing of mesenteric and antimesenteric incisions in the bovine jejunum

Paired incisions (n = 6 pairs) were made in the jejunum of each of 8 Holstein cows. Pairs consisted of 2-cm transverse incisions, 35 cm apart, at the antimesenteric region and at the mesenteric region. Bursting-wall tension was used to test mechanical strength, and cellular and vascular events of healing were evaluated using histologic examination and microangiography. Healing was evaluated at postoperative hour (POH) 48 in 4 of the cows (group 1) and at POH 96 in the remaining 4 (group 2). Evidence of leakage of intestinal contents was not found in any of the cows. At POH 48 and 96, bursting-wall tension was significantly (P less than 0.001) greater in the intestinal segments with antimesenteric incisions than in those segments with mesenteric incisions. Disruption of normal vasculature was seen at mesenteric and antimesenteric sites; ingrowth of vessels, reformation of vascular plexuses, and development of collateral circulation were observed at POH 96. Granulation tissue was observed at POH 96 at the antimesenteric and mesenteric sites, and early stages of mucosal reepithelialization were seen in several sections at POH 48. Better apposition of tissue layers was seen in antimesenteric incisions, but mucosal eversion was evident in several mesenteric incisions. Some sections examined from cows at POH 96 had complete bridging of mucosa, submucosa, and muscularis layers at the antimesenteric location. Inflammatory cells were observed along the incision and at the mucosal and serosal surfaces in many of the sections. Deposition of new collagen was not appreciable in any section at POH 48 or 96.