Megaesophagus

Dilatation of the esophagus has been reported in inbred Swiss ICRC/HiCri mice. These mice have smooth muscle in the abdominal segment of the esophagus, in contrast to the normal configuration of smooth muscle in the lowermost portion, adjacent to the stomach. In addi­tion, the mice have aplasia of the myenteric plexus, with fibrosis. The condition was most severe in older mice. A similar syndrome has been observed among aging 129S4/SvJae mice, with significant mortality associated with esophageal impaction. There are now a number of mutant mice that develop megaesophagus, which are revealing a number of pathogenetic mechanisms under­lying this complex disease.