Multiple bowel atresias after syngeneic fetal small bowel transplantation in rats

The aim of this study was the assessment of atresia formation after syngeneic fetal small bowel transplantation (SBTx) to clarify its pathogenesis.

Seventy Lewis rat fetuses (gestational age, 18 to 19 days) were obtained by hysterotomy, and a 30-mm long section of small bowel was excised from each fetus. Each bowel graft was then transplanted into the space between the peritoneum and the rectus abdominis in 70 adult Lewis rats to expose the grafts to ischemic stress. Transplantation was successful in 63 of 70 grafts (90%). Successfully transplanted bowel grafts were harvested for macroscopic and microscopic examination 10 days posttransplantation.

Of the successfully transplanted grafts, only two (3%) were atresia free; 127 atretic segments were found in the remaining 61 grafts. Twenty-four grafts (38%) had a single atresia comprised of membranous stenosis (MS) in two, membranous atresia (MA) in 10, and blind ends (BEs) with or without a connecting tissue remnant in 12. Thirty-seven grafts (59%) had multiple atresias, comprised of MS, MA, or both in six, BEs alone in seven, and a combination of BEs with MS or MA in 24.

Our model is the first to succeed in inducing experimentally membranous stenosis and a high incidence (59%) of multiple atresias. These results suggest that bowel ischemia is responsible for multiple bowel atresia formation.