A prospective evaluation of the pathogenesis of detrusor instability in women, using electron microscopy and immunohistochemistry

Objective To characterize the types of detrusor smooth muscle junctions in the bladders of women with detrusor instability and in a control group with out, and to assess whether there are differences in the cell junctions betw een these groups. Patients and methods The study included 13 women with detrusor instability (median age 57 years, range 32-86) and 11 control women (median age 50 year s, range 33-62). Bladder biopsies were taken from each participant, process ed for electron microscopy and immunohistochemistry (using a labelled antib ody to vinculin) and analysed by investigators who were unaware of the pati ents' diagnoses. Results Adherens (intermediate) junctions in classic and rudimentary forms were present in all biopsies from patients and controls. Adherens junctions and dense plaques occupied almost the complete cell border in most samples . Complete immunohistochemistry was possible in seven patients and five con trols. In almost every detrusor smooth muscle cell studied, there was stain ing of the entire cell border with labelled antibody to vinculin in all bio psies. Conclusions This study provides evidence against an ultrastructural basis f or idiopathic detrusor instability based on possible differences in detruso r smooth muscle intercellular junctions. Virtually the entire cell membrane of detrusor smooth muscle fibres is occupied by adherens junctions in clas sic and rudimentary forms, and with dense plaques present in samples from w omen with an unstable bladder and from controls. There was no junction dete cted in those with instability that was not present in the control group. T he adherens junctions in the bladder facilitate mechanical coupling between cells.