[Scanning electron microscopic studies of the urinary bladder of sows with special reference to a Eubacterium suis infection].

Scanning electron microscopy was performed on bladder biopsies from 20 sows with cystitis. Results were compared with those of healthy control animals. Biopsy specimens were taken from nine sows infected only with commensal bacteria (E. coli, streptococci, staphylococci) and from 11 sows, where Eubacterium suis (E. suis) was involved in urinary tract infection and had caused a haemorrhagic cystitis. Increased losses of normal superficial cells covered with microplicae could be seen depending on the degree of cystitis. Desquamation of the surface layer exposed smaller cells patterned with short microvilli. These cells were presumed to be immature intermediate cells and goblet cells. Goblet cells were found only in infected organs. The varying surface structure of epithelial cells in relation to receptor quality is important for the bacterial adherence to bladder mucosa. All examined bladders infected with E. suis showed a total loss of superficial cells. Luminal cells covered with multiple short microvilli were accompanied by cells with long pleomorphic processes. Accumulating cell necrosis was indicated by a smooth surface structure. Funnel-shaped orifices between the epithelial cells were identified as excretory ducts of mucus-filled cysts, which are formed by the confluence of degenerating goblet cells. E. suis infection of the porcine bladder causes more severe alterations than infections due to other bacteria. However, debilitation of the urothelium due to previous infection is necessary to support infection of the bladder with E. suis.