1979 Volume 19 Issue 1 Pages 31-36
Congenital megacolon rats were found in offspring of a female albino rat crossed with a wild male. In megacolon rats, their eyes were dark and their coats were almost white with only small pigmented spots on the heads. These rats could not survive more than 35 days after birth because of the fecal stasis. At autopsy of these rats, the upper side of the intestine enlarged and the anal side of that narrowed. Narrow segments of the lower intestine were found in the lower colon, in the total colon or in the lower small intestine and total colon in respective rats. From histological observations, it was confirmed that myenteric ganglion cells of the narrow segment were absent. And it was demonstrated by genealogical analysis that the congenital aganglionosis was controlled by an autosomal recessive gene. We named these megacolon rats Congenital Aganglionosis Rat and this gene Spotting Lethal, sl. It has since been maintained by heterozygous brother-sister matings.