SUBMUCOSAL COLLAGEN IN EXPERIMENTAL GASTROSCHISIS

Gastroschisis is a congenital anomaly in which the intestines are expo sed to amniotic fluid throughout fetal life. Previous studies in anima l models have demonstrated smooth muscle thickening and decreased cont ractility, epithelial dysfunction, and submucosal thickening. The pres ent studies were done to further define the mechanism of submucosal ch anges by investigating collagen deposition and gene expression in a ra bbit model. Gastroschisis was surgically created in fetal rabbits at 2 4 days gestation (term is 31 days). Sham-operated and unoperated fetus es served as controls. Fetuses were sacrificed and bowels were harvest ed at 26, 28, and 31 days gestation, Animal weight and gross and histo logic appearance were assessed, Submucosal collagen content was measur ed using the van Geison stain. In situ hybridization of the expression of alpha (1) procollagen RNA was done to determine the distribution a nd source of submucosal collagen. At term, submucosal thickening was p resent in animals with gastroschisis, associated with a significantly increased collagen content. Collagen distribution was also more diffus e in the gastroschisis animals than in controls. In situ hybridization revealed procollagen expression in round cells located in the submuco sa and not in smooth muscle. These cells did not resemble fibroblasts, and their identity is uncertain, Experimental gastroschisis is charac terized by submucosal thickening which is associated with changes in c ollagen, including increased deposition and more diffuse distribution in the submucosa. The cells responsible for production of procollagen are round, nonfibroblast cells which are located in the submucosa and not in the smooth muscle layer. These findings may have some importanc e in understanding the mechanisms responsible for intestinal malfuncti on in infants with gastroschisis. (C) 1996 Academic Press, Inc.