树鼩脊髓Onuf核的形态学研究

A MORPHOLOGICAL STUDY OF THE ONUF'S NUCLEUS IN THE LREESHREW—F-HRP, CB-HRP AND FLUORESCENT DOUBLE LABELLING STUDY

本文用CB-HRP、F-HRP、FB及NY首次对两性树鼩Onuf核(ON)的构筑进行了比较研究,结果显示:(1) 两性的ON主要位于脊髓L_6至S_1节段前角的腹外侧一卵圆形区内;(2) 横切面上,ON的树突呈定向分布,达侧索、前索白质、Ⅰ-Ⅹ层及软膜下。水平切面上,可见ON内有十分显著的纵向树突束,与之垂直的横向树突在侧索白质内交织成网;(3) ON的性差表现在细胞数量上,雄性多于雌性,差异有高度显著性;(4) 阴部神经的跨节标记纤维分布于同侧与对侧Ⅱ—Ⅴ层内侧及灰质后连合。肛门外括约肌与尿道外括约肌的跨节标记纤维主要见于同侧Ⅱ—Ⅳ层内1/3与外2/3交界区;(5) 荧光法显示了单块会阴肌运动神经元在ON内的局部定位;(6) 电镜观察到ON白质树突育突触结构,突触小泡以清亮圆形和卵圆形为主。文中还对ON的比较解剖及ON在排泄功能与性功能方面的重要生理特性作了初步讨论。

In order to study the morphology of the Onuf's nucleus, 68 adult male and female tree shrews were used in the present study. The results are as follows: labelled cells of the Onuf's nucleus in both sexes were found primarily in the ventrolateral of the ventral horn of segments L_6-S_1 of the spinal cord. Numerous transverse dendrites from the nucleus formed small bundles and projected toward the lateral and ventral funiculus, laminae Ⅰ-Ⅹ and pin mater. The longitudinal dendrites from the nucleus forming a dense network ran rostrocaudally within the nucleus, many transverse dendrites ran medially at a right angle and crossed the ventral gray matter to the white matter, some transverse dendrites extended laterally to the lateral funiculus, where they formed a dense network. The Onuf's nucleus presented a sexual difference in the number of the labelled cells, i.e. the number of the labelled cells in the male animal was significantly larger than in the female. The labelled afferent fibers of the external anal sphincter and the external urethral sphincter muscles were detected ipsilaterally in the border region between medial 1/3 and laterat 2/3 of laminae Ⅱ-Ⅴ. Fluorescent method showed topographic localization of the motoneurons in Onuf's nucleus innervating individual perineal muscles. The axo-dendritic synapses with agranular spherical or ellipsoidal vesicles in presynaptic components were found on the labelled white matter dendrites. It is suggested the activity of the Onuf's nucleus could be regulated, through the paralateral circuit.