Gartych Magdalena, Jackowiak Hanna, Bukowska Dorota, Celichowski Jan
Department of Neurobiology, Poznań University of Physical Education, Poznań, Poland.
Department of Histology and Embryology, Poznań University of Life Sciences, Poznań, Poland.
Front Neuroanat. 2021 Oct 1;15:734555. doi: 10.3389/fnana.2021.734555. eCollection 2021.
This study sought to investigate the sexual dimorphism of muscle spindles in rat medial gastrocnemius muscle. The muscles were cut transversely into 5-10 and 20 μm thick serial sections and the number, density, and morphometric properties of the muscle spindles were determined. There was no significant difference ( > 0.05) in the number of muscle spindles of male (14.45 ± 2.77) and female (15.00 ± 3.13) rats. Muscle mass was 38.89% higher in males (1.08 vs. 0.66 g in females), making the density of these receptors significantly higher ( < 0.01) in females (approximately one spindle per 51.14 mg muscle mass vs. one per 79.91 mg in males). There were no significant differences between the morphometric properties of intrafusal muscle fibers or muscle spindles in male and female rats ( > 0.05): 5.16 ± 2.43 and 5.37 ± 2.27 μm for male and female intrafusal muscle fiber diameter, respectively; 5.57 ± 2.20 and 5.60 ± 2.16 μm for male and female intrafusal muscle fiber number, respectively; 25.85 ± 10.04 and 25.30 ± 9.96 μm for male and female shorter muscle spindle diameter, respectively; and 48.99 ± 20.73 and 43.97 ± 16.96 μm for male and female longer muscle spindle diameter, respectively. These findings suggest that sexual dimorphism in the muscle spindles of rat medial gastrocnemius is limited to density, which contrasts previous findings reporting differences in extrafusal fibers diameter.
本研究旨在调查大鼠腓肠肌内侧肌梭的性别差异。将肌肉横向切成5 - 10μm和20μm厚的连续切片，测定肌梭的数量、密度和形态学特性。雄性（14.45±2.77）和雌性（15.00±3.13）大鼠的肌梭数量无显著差异（>0.05）。雄性大鼠的肌肉质量比雌性高38.89%（分别为1.08 g和0.66 g），使得这些感受器的密度在雌性中显著更高（<0.01）（每51.14 mg肌肉质量约有一个肌梭，而雄性为每79.91 mg一个）。雄性和雌性大鼠的梭内肌纤维或肌梭的形态学特性无显著差异（>0.05）：雄性和雌性梭内肌纤维直径分别为5.16±2.43μm和5.37±2.27μm；雄性和雌性梭内肌纤维数量分别为5.57±2.20μm和5.60±2.16μm；雄性和雌性较短肌梭直径分别为25.85±10.04μm和25.30±9.96μm；雄性和雌性较长肌梭直径分别为48.99±20.73μm和43.97±16.96μm。这些发现表明，大鼠腓肠肌内侧肌梭的性别差异仅限于密度，这与之前报道的肌外纤维直径差异的研究结果形成对比。
