Comparative microscopic anatomy of the urinary bladder of various domestic and wild ruminants

: The Authors focus their interest on the microanatomical differences between urinary bladders of some domestic (sheep and cattle) and wild Ruminantia (roe and chamois). Sixteen urinary bladders of the following species have been studied by Azan, Masson and Weigert staining methods: Three urinary bladders of Ovis aries (L.) and Bos taurus (L.) drawn from animals of both sexes; seven urinary bladders drawn from female of Capreolus capreolus (L.); three urinary bladders from both sexes specimens of Rupicapra rupicapra (L.). It is possible to summarize the data on the compared microanatomy of urinary bladder in the following way: it presents three tunics: mucosa, muscularis and adventitia. The tunica mucosa is composed of lamina propria and transitional epithelium, and presents typical plicae which give a peculiar aspect to the lumen. In roe deer the lamina propria presents several smooth muscle fibers which are organized in an evident "muscularis mucosae" which is absent in all the studied species. The tunica muscularis is composed of two longitudinal (outer and inner) muscle layers and a middle circular layer. In roe this tunica is thicker and more powerful than in other species, and the single layers are more evident because of the presence of many connective septa. The tunica adventitia is composed of loose connective tissue, and some elastic fibers. Unexpectedly, the Chamois, which belongs to wild Ruminants as the roe, does not present a "muscularis mucosae". Therefore the authors suppose that the presence of "muscularis mucosae" in roe could be due to the ethology peculiar of this species which is accustomed to mark the boundary of its territory by staling frequently.