Mierzejewska-Krzyżowska B, Bukowska D, Taborowska M, Celichowski J
Department of Anatomy, Biology and Health Sciences, Gorzów Wlkp., University School of Physical Education, Poznań, Poland.
Anat Histol Embryol. 2014 Jun;43(3):182-9. doi: 10.1111/ahe.12060. Epub 2013 Apr 26.
The sex differences in the number and morphometric parameters of motoneurons in motor nuclei are poorly known. The aim of this study was to determine the differences in the number and size of alpha and gamma motoneurons of the medial gastrocnemius (MG) muscle in male and female Wistar rats. Retrogradely labelled cell bodies of motoneurons of 6 months old animals were studied following a bath of the proximal stump of the transected MG nerve in a horseradish peroxidase solution. The number and soma diameters of male and female MG motoneurons were determined from serial microscopic images of sections. The weight of the brain and spinal cord was on average 17% higher in males than in females. The mean number of motoneurons was 13% higher in males than in females and amounted to 94 and 83 motoneurons, respectively. In each case, the average soma diameters and cross-section areas of motoneurons in motor nucleus were distributed bimodally: motoneurons smaller than 27.5 μm in diameter were recognized as gamma and greater ones as alpha motoneurons. In males, the motor nucleus contained on the average 66 alpha motoneurons, whereas in females, 56 alpha motoneurons, that is the mean number of alpha motoneurons was 17% higher in males. Moreover, the soma diameters of gamma and alpha motoneurons were significantly bigger in males and the difference amounted 9 and 6%, respectively. It is concluded that the number as well as size of alpha and size of gamma motoneurons in the MG motor nucleus are greater in males.
运动核中运动神经元数量和形态测量参数的性别差异鲜为人知。本研究的目的是确定雄性和雌性Wistar大鼠腓肠肌内侧（MG）中α和γ运动神经元数量和大小的差异。在辣根过氧化物酶溶液中浸泡切断的MG神经近端残端后，研究6个月龄动物运动神经元的逆行标记细胞体。从切片的系列显微图像中确定雄性和雌性MG运动神经元的数量和胞体直径。雄性大脑和脊髓的重量平均比雌性高17%。运动神经元的平均数量雄性比雌性高13%，分别为94个和83个。在每种情况下，运动核中运动神经元的平均胞体直径和横截面积呈双峰分布：直径小于27.5μm的运动神经元被识别为γ运动神经元，较大的则为α运动神经元。在雄性中，运动核平均含有66个α运动神经元，而在雌性中为56个，即α运动神经元的平均数量雄性比雌性高17%。此外，雄性γ和α运动神经元的胞体直径明显更大，差异分别为9%和6%。结论是，MG运动核中α运动神经元和γ运动神经元的数量以及大小在雄性中更大。
