Regeneration-induced lengthening of the cut ends of the rat colon.

The transected colon was studied in rats in an attempt to determine whether the regenerating cut ends could be induced to lengthen by delaying or preventing their spontaneous reattachment. When the two cut ends of the defunctionalized colon were separated by a 2-3-cm length of silastic tubing mucosal, luminal and serosal continuity across the gap was restored in 8-10 weeks. Cannulation of one cut end with silastic tubing so placed as to extend 2-3 cm beyond the cut end led to lengthening of the intestine over the exposed end of the tubing by 20 weeks. The area subadjacent to regenerated mucosa filled initially with granulation tissue which was gradually replaced by loose connective tissue containing at times a thin layer of smooth muscle.