Abstract
Macro- and microscopic findings were obtained on cysts formed in the reproductive organs, particularly the mesosalpinx, mesovarium, and fimbria, of 709 cows and 791 sows. The number of cysts totaled 815 for the cows and 525 for the sows, with relative frequencies of 32.3% and 29.3%, respectively. The majority of the cysts measured below 5.9 mm in diameter, with 3 very few large cysts measuring over 10 mm in diameter With regard to the location of the cysts, the highest incidence of cysts was found in the fimbria in cows (81.0%) and in the mesosalpinx in sows (62.9%). In both species, the incidence of the cyst formation in the mesovarium was lower than that in either mesosalpinx or fimbria. So-called parovarian cysts were quite rare. The cysts were classified into 3 types histologically and into 2 types on the basis of cyclic changes in their epithelia. In the latter classification, one type responded to sex hormones, along with the tubal epithelium which was classified as the cyclic change type. The other type did not respond to sex hormones and was classified as the non-cyclic change type. Because of its locality and response to sex hormones, the cyclic change type was regarded as of paramesonephric origin, whereas the non-cyclic change type was of mesonephric origin. Animals with cysts which gave pressure upon the oviducts exhibited histological changes, including partial atrophy or lack of folds in the tubal mucosa.
