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The pathophysiology of pelvic floor disorders: evidence from a histomorphologic study of the perineum and a mouse model of rectal prolapse

Published online by Cambridge University Press:  28 November 2001

RENÉ YIOU
Affiliation:
Faculté de Médecine de Créteil, Faculté des Saints-Pères, Paris, France Service d'Urologie, Faculté des Saints-Pères, Paris, France
VINCENT DELMAS
Affiliation:
Laboratoire d'Anatomie, Faculté des Saints-Pères, Paris, France
PETER CARMELIET
Affiliation:
Center for Transgene Technology and Gene Therapy, Flanders Interuniversity Institute for Biotechnology, University of Leuven, Belgium
ROMAIN K. GHERARDI
Affiliation:
Faculté de Médecine de Créteil, Faculté des Saints-Pères, Paris, France
GEORGIA BARLOVATZ-MEIMON
Affiliation:
Faculté de Médecine de Créteil, Faculté des Saints-Pères, Paris, France
DOMINIQUE K. CHOPIN
Affiliation:
Service d'Urologie, Faculté des Saints-Pères, Paris, France
CLÉMENT-CLAUDE ABBOU
Affiliation:
Service d'Urologie, Faculté des Saints-Pères, Paris, France
JEAN-PASCAL LEFAUCHEUR
Affiliation:
Faculté de Médecine de Créteil, Faculté des Saints-Pères, Paris, France Service de Physiologie, CHU Henri Mondor, Créteil, Faculté des Saints-Pères, Paris, France
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Abstract

The muscle changes related to pelvic floor disorders are poorly understood. We conducted an anatomical and histological study of the perineum of the normal mouse and of a transgenic mouse strain deficient in urokinase-type plasminogen activator (uPA−/−) that was previously reported to develop a high incidence of rectal prolapse. We could clearly identify the iliococcygeus (ILC) and pubococcygeus (PC) muscles and anal (SPA) and urethral (SPU) sphincters in male and female mice. The bulbocavernosus (BC), ischiocavernosus (ISC) and levator ani (LA) muscles could be found only in male mice. Histochemical analysis of the pelvic floor muscles revealed a majority of type IIA fibres. Rectal prolapses were observed only in male uPA−/− mice. The most obvious finding was an irreducible evagination of the rectal mucosa and a swelling of the entire perineal region corresponding to an irreducible hernia of the seminal vesicles through the pelvic outlet. The hernia caused stretching and thinning of the ISC, BC and LA. Myopathic damage, with degenerated and centronucleated myofibres, were observed in these muscles. The PC, ILC, SPA and SPU were not affected. This study provides an original description of a model of pelvic floor disorder and illustrates the differences existing between the perineum of humans and that of a quadruped species. In spite of these differences, the histopathologic changes observed in the pelvic floor muscles of uPA−/− mice with rectal prolapse suggest that prolonged muscular stretching causes a primary myopathic injury. This should be taken into account in the evaluation of pelvic floor disorders.

Type
Research Article
Copyright
© Anatomical Society of Great Britain and Ireland 2001

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