Mechanical properties of pelvic soft tissue of young women and impact of aging.

INTRODUCTION AND HYPOTHESIS: The female pelvic floor is a complex network of ligaments and muscles whose mechanical properties have not been completely understood. The goal of this study is to understand the biomechanical properties of the pelvic floor tissues of young women and the impact of aging. METHODS: Biomechanical uniaxial tension tests were performed on pelvic floor tissues (ligaments and organs) of six young female cadavers (average 29 years old). Results have been analyzed in order to define the characteristics of the mechanical properties of young pelvic soft tissues. Results have been compared with those in the literature in order to understand the similarities and discrepancies between young and old patients. RESULTS: Damageable, nonlinear elastic biomechanical behavior is observed. The variation in stiffness among the pelvic floor organs could be shown. Ligaments and the vaginal wall are the most rigid organs, whereas the rectum and bladder tend to be less rigid (approximately two times less rigid for small deformations and three times less rigid for large deformations). This study shows that ligaments and the vaginal wall of young women have similar mechanical behavior while those of older women differ. Furthermore, young women's tissues differ slightly from older women's tissues. CONCLUSIONS: Results show that aging and possibly diverse "trauma" have an impact on modifying the mechanical behavior of pelvic floor tissues. Over time pelvic floor ligaments and vaginal tissues will differentiate and acquire different mechanical behavior, as seen within the literature in older cadavers.

Comparative analysis of pelvic ligaments: a biomechanics study.

INTRODUCTION AND HYPOTHESIS: Pelvic organ prolapse (POP) affects one third of women of all ages and is a major concern for gynecological surgeons. In pelvic reconstructive surgery, native ligaments are widely used as a corrective support, while their biomechanical properties are unknown. We hypothesized differences in the strength of various pelvic ligaments and therefore, aimed to evaluate and compare their biomechanical properties. MATERIALS AND METHODS: Samples from the left and right broad, round, and uterosacral ligaments from 13 fresh female cadavers without pelvic organ prolapse were collected. Uniaxial tension tests at a constant rate of deformation were performed and stress-strain curves were obtained. RESULTS: We observed a non-linear stress-strain relationship and a hyperelastic mechanical behavior of the tissues. The uterosacral ligaments were the most rigid whether at low or high deformation, while the round ligament was more rigid than the broad ligament. CONCLUSION: Pelvic ligaments differ in their biomechanical properties and there is fairly good evidence that the uterosacral ligaments play an important role in the maintenance of pelvic support from a biomechanical point of view.

[Contractile properties of smooth muscle cells of the horns, cervix and broad ligament of the pig uterus]. / Sokratitel'naia svoistva gladkomyshechnykh kletok roga, sheiki i shirokoi sviazki matki svin'i.

Physiological properties of the pig uterus smooth muscle of different regions revealed similarities as well as differences depending on the phase of reproduction cycle. Smooth muscle of the pregnant pig horn contains a large number of beta-adrenoreceptors important for inhibition of the uterine contractions. At the late pregnancy their number decreases while the smooth muscle of the uterine cervix loses its sensitivity to acetylcholine, histamine and oxytocin which is important for induction of parturition.

Characteristics of the electromyogram recorded from the mesometrium of the pregnant ewe from 106 days' gestation to delivery: similarities with and differences from the electromyogram obtained from the myometrium.

Electromyographic recordings from 12 pregnant sheep were analyzed in four gestational age groups (106 to 115, 116 to 125, 126 to 135, and 136 to 145 days) and by the day of delivery. Mesometrial electromyographic activity was present in all animals studied. Contracture activity was synchronous in both mesometrium and myometrium. The frequency distribution of electromyographic events of different duration in the mesometrium was qualitatively identical to that recorded from the myometrium. The frequency of events less than 180 seconds was greater in the myometrium, while no difference was observed in contracture frequency. Mean contracture duration in myometrium and mesometrium shortened as gestation progressed (p less than 0.01), and was of significantly shorter duration on the day of delivery when compared with all gestational age intervals (p less than 0.05). Except at 135 to 145 days' gestation and at the day of delivery, myometrial contractures were of significantly longer duration than mesometrial contractures. The presence of the endometrium and fetal membranes in the pregnant ewe may stimulate the myometrium, and account for the difference observed. In vivo recording of mesometrial electromyographic activity may provide an opportunity to study the paracrine regulation of myometrial activity.

[The characteristics of the hemodynamics and oxygen regimen of the rat uterus]. / Osobennosti gemodinamiki i kislorodnogo rezhima matki krys.

For biomicroscopic study of architectonic and hemodynamic features of uterine vascular bed wide ligation was carried out. It is shown that the vascular bed serves for blood deposition with cyclic change of inflow and outflow intensity. A rhythmic hypoxia results in a decrease of PO2 in the myometrium. The revealed biorhythm is considered evolutionary, determining physiological mechanism of plastic supply of generative function and development of the fetus resistance to hypoxia.

Role of mesovarium and mesosalpinx in counter current exchange of hormones.

On the base of own studies with counter current transfer of steroid hormones and PGF2 alpha and the data taken from the literature it is suggested that two parts of broad ligament of the uterus i.e. mesovarium and mesosalpinx are not only morphological structures keeping the ovary, oviduct and ovarian vasculature, but that they may take part in hormonal regulation of the ovarian function.

An analysis of the characteristics of the electromyogram recorded from the mesometrium in the ovariectomized nonpregnant ewe and its similarities with and differences from the electromyogram obtained from the myometrium: the effect of estrogens.

Mesometrial and myometrial electromyograms have been recorded from ovariectomized nonpregnant ewes. After infusion with saline solution, the frequency of electromyographic events lasting less than 180 seconds in the myometrium was not different from the frequency of their occurrence in the mesometrium. During infusion of estradiol at 100 micrograms/24 hours, the frequency of events less than 180 seconds increased significantly in the myometrium but was unchanged in the mesometrium. Contracture activity (electromyographic events lasting more than 180 seconds) was significantly greater in the mesometrium than in the myometrium before estradiol administration. During estradiol infusion, contracture activity remained unchanged. These findings suggest that the mesometrial muscle may be a useful model to study the effects of various stimulators and inhibitors of uterine muscle function in the absence of stretch and local paracrine effects that occur in the uterus itself.