STEREOLOGICAL ANALYSIS OF THE URETHRA IN SEXUALLY INTACT AND SPAYED FEMALE DOGS

The perfusion-fixed urethrae of 5 sexually intact nulliparous and 5 ov ariohysterectomized beagles were analyzed stereologically. Different u rethral tissue components were estimated stereologically in each of th e three proximal urethral quarters and compared between the two groups of dogs. Considerable individual variability within all groups was ob served. In all the three urethral quarters considered, average smooth muscle and connective tissue volumes were generally lower in spayed th an in intact animals, both in absolute and relative terms. However, on ly the difference between the mean relative volumes of urethral quarte r I was statistically significant. In contrast, mean absolute and rela tive volumes of the vascular plexus were generally greater in the ovar iohysterectomized dogs as compared to the animals of the other group - deviations in statistical relevance concerning the first urethral qua rter were noted. Mean epithelial and striated muscle volumes did not v ary essentially between the spayed and intact group of dogs. Despite t he fact that all findings were not always statistically meaningful, ou r research nevertheless demonstrates that ovariohysterectomy decreases smooth muscle mass and connective tissue; it also elevates vascular p lexus volumes in the urethra of spayed animals. Moreover, our results imply a general weakening of the urethral wall as a sequel to ovariohy sterectomy, and this, in turn, could be seen to affect the closure mec hanism of the urethra.