The Urethral Rhabdosphincter, Levator Ani Muscle, and Perineal Membrane: A Review

Figure 7

Horizontal sections in a 76-year-old woman. Panel (a) (elastica-Masson staining) includes the urethra (UR), crus clitoris (CC), rhabdosphincter (RS), urethrovaginal sphincter (UVS), and levator ani (LA): the anterior side of the body corresponds to the upper side of the figure. Panel (b) (immunohistochemistry for smooth muscle actin) is a higher-magnification view of the square marked B in panel (a), while panel (c) (immunohistochemistry for desmin) and panel (d) (immunohistochemistry for smooth muscle actin) are higher-magnification views of the square marked CD in panel (a). The levator ani is accompanied by a smooth muscle-rich fascia (panel (b)). The urethrovaginal sphincter is composed of striated muscle fibers (positive in panel (c); negative in panel (d)), accompanied by abundant irregular elastic fibers (panel (e)). The rectovaginal septum between the vagina (VAG) and rectum (REC) is replaced by veins. Scales bars: 10 mm in panel (a); 1 mm in panels (b), (c), and (d); 0.1 mm in panel (e).