ELASTIN MORPHOLOGY IN NORMAL AND OBSTRUCTED GUINEA-PIG BLADDERS - LOCALIZATION OF ELASTIN TO THE TRIGONE

Elastin is the major component of elastic fibers in aortic tissue and has been suggested to be important for the stretch and recoil of the b ladder. We have mapped the histologic distribution of elastin througho ut the entire guinea-pig bladder as well as changes in the distributio n of elastin during bladder-outlet obstruction. We used an animal mode l in which a jeweler's ring is placed around the urethra of the young guinea pig. As the animal grows, outlet obstruction is gradually induc ed, and the bladder gradually increases in total weight to as much as 8-fold that of controls. We localized the elastin histologically in no rmal and obstructed bladders by serially sectioning entire bladders an d staining the sections with an elastin-specific stain, Verhoff-van Gi eson stain (VVG). Surprisingly, we found that the elastin was predomin antly localized only to the trigone of the bladder and that the elasti n in this area was increased during obstruction. These results are con sistent with the predominantly mesodermal embryologic origin of the tr igone, since mesodermal tissues are more often associated with elastin expression.