The Urethral Rhabdosphincter, Levator Ani Muscle, and Perineal Membrane: A Review
Figure 1
Frontal sections in a 78-year-old man. Panels (a)–(c) and (e) show elastica-Masson staining (striated muscles: red; collagen fibers: green; elastic fibers: black), while panel (d) shows immunohistochemistry for S100 protein using a section close to that in panel (c). Panel (a) includes a longitudinal section of the urethral wall (UR), while panel (c) is located 3 mm behind panel (a). Panel (b) (or panel (e)) is a higher-magnification view of the square in panel (a) (or panel (c)). A thick fascial structure (arrowheads in panels (a) and (c)), containing abundant elastic fibers (black wavy lines in panels (b) and (e)) and smooth muscles (SM; red-gray fibers in panels (b) and (e)), is evident between the rhabdosphincter area (RS) and the inferomedial edge of the levator ani (LA). In panel (d) (section adjacent to panel (c)), S100-positive nerves are seen passing through the urogenital hiatus. Panel (f), a higher-magnification view of the center of the rhabdosphincter area on the left-hand side of panel (a), displays an elastic fiber cage surrounding the striated muscle fibers. Scale bars: 10 mm in panels (a), (c), and (d); 0.1 mm in panels (b), (e), and (f). BP: bulbus penis; BS: bulbospongiosus muscle; CG: Cowper’s gland; DTP: deep transverse perineal muscle; IC: ischiocavernosus muscle.
