RESUMO
The progress of jejunal damage and recovery in the course of mesenteric ischemia-reperfusion injury in rats at different time periods was investigated. Mesenteric ischemia lasting 1h followed by 1h of reperfusion caused a significant disintegration of the mucosa, reduction of the muscular layer and diminution of the wall thickness. The loss of epithelium included enterocytes, goblet cells and Paneth cells. Paradoxically, increasing numbers of serotonin-producing cells and the beginning of regenerative processes, expressed by significantly higher proliferation, were recorded in the epithelium during this period. Disintegration of connective tissue and massive degranulation of serotonin-positive cells were found in the lamina propria. After 24h of reperfusion, restitution of the mucosa was found, expressed by normal villous morphology and re-epithelialization. However, some parameters were still significantly affected even more than in the acute phase of reperfusion. In the epithelium, decreased numbers of Paneth cells and increased population of serotonin-producing cells were found. The greatest proliferation of connective tissue cells and intensified reduction of the muscular layer were also detected in this reperfusion period. After 30 days of reperfusion, moderate damage remained, but only the increased number of Paneth cells and decreased number of serotonin-producing cells in the lamina propria were significant.