Chylous Ascites in Newborn Mice.

In I958, during breeding experiments in the Department of Genetics at Cambridge, a small -proportion of newbom offspring of backcross matings of the gene ragged (Ra, Slee, I957) developed a swollen belly. The affected animals appeared normal at birth but about 24 hours after they had begun to suckle their abdomens became swollen with an accumulation of milk-like fluid in the peritoneal cavity. During the first 5 days after birth the abdominal wall ofnormal mice is relatively transparent, and the stomach, intestines, and other viscera are clearly visible from the ventral surface.