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

Abstract

To characterize the types of detrusor smooth muscle junctions in the bladders of women with detrusor instability and in a control group without, and to assess whether there are differences in the cell junctions between these groups. The study included 13 women with detrusor instability (median age 57 years, range 32-86) and 11 control women (median age 50 years, range 33-62). Bladder biopsies were taken from each participant, processed for electron microscopy and immunohistochemistry (using a labelled antibody to vinculin) and analysed by investigators who were unaware of the patients' diagnoses. 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 controls. In almost every detrusor smooth muscle cell studied, there was staining of the entire cell border with labelled antibody to vinculin in all biopsies. This study provides evidence against an ultrastructural basis for idiopathic detrusor instability based on possible differences in detrusor smooth muscle intercellular junctions. Virtually the entire cell membrane of detrusor smooth muscle fibres is occupied by adherens junctions in classic and rudimentary forms, and with dense plaques present in samples from women with an unstable bladder and from controls. There was no junction detected in those with instability that was not present in the control group. The adherens junctions in the bladder facilitate mechanical coupling between cells.