COMPARATIVE MORPHOLOGICAL CHARACTERISTICS OF THE LEVATOR ANI MUSCLE IN MAN AND RAT

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Background. Currently, for the study of pelvic floor disorders, such as urinary incontinence, faeces, pelvic prolapse, are used as a model of white laboratory rats. Aim. From the point of view of the justification of the modeling of the symptoms of pelvic floor disorders, we set the goal of the study: to make a comparative analysis of the structure of the muscle that raises the anus in a man and a rat. Material and Methods. In our work we used methods of dissection of cadaveric material, light microscopy, morphometry of muscle fibers, histochemistry. Results and Discussion. As a result, the main forms of the muscle structure that lifts the anus in rats of both sexes are described: a horseshoe shaped in males, «0» shaped in females. The basic forms of muscle fibers of the muscle that lifts the anus are also determined: in humans, they have a rectangular and rounded section; in rats, tricephalus or polygonal shape. Histochemical examination showed the presence in rats in m. levator ani of predominantly glycolytic fibers in contrast to people where the muscle lifting the anus is represented predominantly by oxidative fibers. Conclusions Histochemical methods revealed fast and slow muscle fibers in m. levator ani rats. Glycolic fibers (type II) are represented in the predominant quantity in rats of both sexes in comparison with oxidative (type I). People m. levator ani predominantly consists of slow oxidizing fibers (Bouorcier, Shafik 1999). This feature may be related to the verticalization of the position, the reduction of the caudal vertebrae and the peculiarity of the location of the pelvic organs with respect to the center of gravity of the earth. Conclusions. Histological analysis of the metabolic profile of muscle fibers m. levator ani of humans and rats, features of the ultrastructural and macroscopic structure on the one hand makes it possible to use the white rat as an object for experimental study of the symptoms of incontinence of urine and feces, prolapse of internal organs; but on the other hand, it is necessary to take into account the functional peculiarity of the prevailing number of muscle fibers, the ability to train muscles to achieve the effect of conservative treatment of incontinence symptoms.