Histotopographic study of the pubovaginalis muscle.

The pubovaginalis muscle (PVM) is one of the described components of the pubococcygeus muscle. The aim of the study was to investigate its topography and histological characteristics. After in situ formalin fixation, the pelvic viscera were removed from 16 female cadavers (range of age: 54-72 years). Serial macrosections of the pelvic viscera and pelvic floor complex, cut in horizontal (8 cases) and coronal (8 cases) planes, underwent histological and immunohistochemical study. PVM was identified in 13/16 (81%) specimens. In both coronal and transverse sections it appears as a layer of muscular tissue at the passage of the inferior and middle thirds of the vagina, along the lateral vaginal walls. In coronal sections, it appeared as a fan-shaped layer of muscular tissue, arising from the pubococcygeus muscle, running with an oblique course towards the lateral vaginal walls. The mean (± SD) thickness of the PVM was 1.8 (± 1.25) mm. In the transverse sections, a bundle of muscle fibres with oblique course splits from the medial margin of the pubococcygeus muscle towards the lateral walls of the vagina, mingling with the outer longitudinal fibers of the muscular layer of the vagina. Immunohistochemical stainings showed that it consisted predominantly of striated muscle fibers. The PVM could represent anatomical evidence of a functional connection between the vagina and the muscular system of the pelvic floor.