Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Diego, Sanford Consortium for Regenerative Medicine, La Jolla, CA 92037.
Department of Women's Health, The University of Texas at Austin, Austin, TX 78712.
J Biomech Eng. 2024 Oct 1;146(10). doi: 10.1115/1.4066090.
Skeletal muscle architecture is a strong predictor of in vivo functional capacity and is evaluated in fixed tissues, accommodating the study of human muscles from cadaveric donors. Previous studies evaluating the pelvic floor muscles (PFMs) demonstrated that the rat is the most appropriate small animal model for the study of female PFM architecture, but the rat's suitability for the study of male PFMs is undetermined. We aimed to determine (1) whether PFM architecture exhibits sexual dimorphism in rats or humans, and (2) if the rat is also a suitable animal model for the study of male human PFMs. PFMs were fixed in situ and harvested en bloc from male and female cadaveric donors and 3-month-old male and female Sprague-Dawley rats. Three architectural parameters influenced by species size were used to compare male versus female PFMs within species, while four size-independent measures compared species within sex. All comparisons were made with two-way analysis of variances and Tukey's multiple comparisons tests post hoc. Sarcomere length (rats and humans, p = 0.016 and = 0.002) and normalized fiber length (rats, p < 0.001) were significantly larger in male PFMs. Three of the size-independent measures exhibited similar species trends in both sexes, while the size-independent sarcomere length measure (Ls/Lso) differed between male rats and humans (p < 0.001). Thus, sexual dimorphism is present in rat and human PFM architecture, and the male rat is suitable for studies of human male PFMs.
骨骼肌结构是体内功能能力的强有力预测指标，并在固定组织中进行评估，以适应对尸体供体的人体肌肉进行研究。以前评估盆底肌（PFMs）的研究表明，大鼠是研究女性 PFM 结构的最合适的小型动物模型，但大鼠是否适合研究男性 PFMs 尚不确定。我们旨在确定（1）PFMs 在大鼠或人类中是否存在性别二态性，以及（2）大鼠是否也是研究男性人类 PFMs 的合适动物模型。PFMs 原位固定并从男女尸体供体和 3 月龄雄性和雌性 Sprague-Dawley 大鼠中整块收获。使用三个受物种大小影响的结构参数来比较同一物种内的雄性和雌性 PFMs，而四个独立于大小的测量值则比较同一性别内的物种。所有比较均采用双因素方差分析和事后 Tukey 多重比较检验。肌节长度（大鼠和人类，p=0.016 和 p=0.002）和归一化纤维长度（大鼠，p<0.001）在雄性 PFMs 中显著更大。三个独立于大小的测量值在两性中表现出相似的物种趋势，而独立于大小的肌节长度测量值（Ls/Lso）在雄性大鼠和人类之间存在差异（p<0.001）。因此，大鼠和人类 PFM 结构存在性别二态性，雄性大鼠适合研究人类男性 PFMs。
