Mierzejewska-Krzyżowska Barbara, Celichowski Jan, Bukowska Dorota
Department of Anatomy, Biology and Health Sciences, Poznań University of Physical Education, Gorzów Wlkp., Poland.
Department of Neurobiology, Poznań University of Physical Education, Poznań, Poland.
Ann Anat. 2019 Jan;221:93-100. doi: 10.1016/j.aanat.2018.09.002. Epub 2018 Sep 18.
There are many reports describing sexual dissimilarities in the CNS, particularly in the brain and cortical regions. However, knowledge regarding sexual dissimilarities in the spinal cord and in particular in the hindlimb muscle-motoneuron connectivity controlling locomotion is limited. In order to recognise sex differences in the architecture of the medial gastrocnemius (MG) motor nucleus in rats of the same age, retrograde-labelled motoneurons were identified following a bath of the proximal stump of the transected MG nerve in horseradish peroxidase. The rostrocaudal distribution of motoneurons along the spinal cord and on transverse sections as well as the size and density of motoneurons in the motor nucleus were determined from serial microscopic images. It was shown that the MG pool extended throughout the L4-L6 segments, with a length that was 32% greater in males. The position of the moto pool within the ventral horn of the spinal cord transversal sections was also different in both sexes: the pool was located more dorsally and laterally in males. Three size categories of motoneurons with different soma diameters were distinguished: α (27.5-40.0μm), α (>40.0μm) and γ (<27.5μm). The density of α (α and α) motoneurons as well as γ motoneurons was higher in females, by about 13% and 23%, respectively. The number of α motoneurons was 8% higher in females, whereas there were 46% more α motoneurons in males. The most significant differences in the distribution concerned α motoneurons, which revealed a lower density in the rostral parts of the MG motor nucleus in females. It was therefore concluded that the length of the MG motor nucleus was shorter, whereas the mean density of α and γ motoneurons was higher in females.
有许多报告描述了中枢神经系统（CNS）中的性别差异，尤其是在大脑和皮质区域。然而，关于脊髓中，特别是控制运动的后肢肌肉运动神经元连接方面的性别差异的知识却很有限。为了识别同年龄大鼠腓肠肌内侧（MG）运动核结构中的性别差异，在辣根过氧化物酶中浸泡横断的MG神经近端残端后，对逆行标记的运动神经元进行了鉴定。从系列显微镜图像中确定了运动神经元沿脊髓的前后分布、在横切面上的分布，以及运动核中运动神经元的大小和密度。结果表明，MG运动神经元池贯穿L4-L6节段，其长度在雄性中比雌性长32%。在脊髓横切面上，运动神经元池在腹角内的位置在两性中也有所不同：在雄性中，运动神经元池位于更靠背侧和外侧的位置。区分出了三种不同体直径大小的运动神经元类别：α（27.5-40.0μm）、α（>40.0μm）和γ（<27.5μm）。雌性中α（α和α）运动神经元以及γ运动神经元的密度分别高出约13%和23%。雌性中α运动神经元的数量高出8%，而雄性中α运动神经元则多出46%。分布上最显著的差异涉及α运动神经元，雌性MG运动核头端部分的α运动神经元密度较低。因此得出结论，雌性的MG运动核长度较短，而α和γ运动神经元的平均密度较高。
