Female perineal membrane: a study using pelvic floor semiserial sections from elderly nulliparous and multiparous women.

To describe the architecture and topohistology of the female perineal structures, especially the perineal membrane (PM), we examined frontal sections (one side) and horizontal or transverse sections (another side) of 15 bisectioned pelvic floors. The PM, notably comprising elastic fibers, extended mediolaterally or transversely on the immediately inferior side of the rhabdosphincter area. More posteriorly, the elastic fibers more tilted along the long axis of the vagina and became lining the lateral vaginal wall as a fibrous skeleton. The compressor urethrae and urethrovaginal sphincter were embedded in and interdigitated with the PM. The elastic fiber architecture of the PM was similar to the rectovaginal septum. We hypothesize that the PM plays a role of a shock-absorber at the interface between the levator ani and distalmost vagina. A standard diagram of the female perineal structures is necessary to be revised.