RESUMEN
Whole-mount preparations of urinary bladders stained with a modified Giemsa technique were obtained from three rodent species (Guinea-pig, Calomys callosus and the C57/BLJ isogenic mouse) to identify andestimate the relative number and size of ganglionic neurons within the wall of the organ. The istribution of the ganglia was not uniform among the three species: ganglia were concentrated around the ureteral orifices in the Guinea-pig, they were scattered throughout the organ in Calomys callosus, and they were oncentrated near the internal urethral orifice in the C57/BLJ mouse. In the Guinea-pig, the size of approximately 50 percent of the neurons lie in the range of 200 to 300 microns2. In Calomys callosus, 40 percent of the neurons lie in the range of 200 to 250 microns2, with 28 percnet in the range of 50 to 100 microns2. For the C57/BLJ mouse, approximately 60 percent of the neurons have an area of 250 to 400 microns2