Figure 7.

Thickness of the muscle layer indicated by the number of piling cells in the muscle layers of the homozygous endothelin ETB receptor null rat (ETB(−/−)R) compared with the homozygous wild type ETB(+/+)R. (A) Cross section of the caecum in the ETB(+/+)R and ETB(−/−)R stained with toluene blue. (B) Number of smooth muscle cells in the lower part of the ileum (distended segment), caecum, and colon (constricted segments) of the ETB(+/+)R and the ETB(−/−)R. Each column represents the mean (SEM) of three experiments. *p<0.05, **p<0.01.