Does nonfixation of an atretic colon predict Hirschsprung 's disease?
An early gestational atresia, occurring before secondary retroperitoneal fixation of the colon at approximately 11 weeks may result in interruption of caudal migration of enteric nerves manifesting as Hirschsprung's disease distal to the atresia. Moreover, the aganglionosis may be predicted by a foreshortened, nonfixed colon coiled in the pelvis. Thus, biopsy of the colon should be performed at initial exploration in all cases of atresia in which the colon is not properly fixated to avoid immediate or delayed anastomosis to an aganglionic colon.
The genetic background of the nonmutant PVG rats does not influence the genetic and phenotypic inheritance of CKD from mutant Lewis polycystic kidney rats. A single recessive mutation incapacitated the gene, which relaxed its functional constraints, and led to formation of multiple cysts in the kidneys of the homozygous mutant rats.