猫骶髓“内脏面”传出神经元和二级传入神经元的分布

应用HRP和荧光金标记技术,在荧光显微镜下观察了猫骶體“內脏面”的传出神经元和二级传入神经元的分布?咀偌磷⑷肱枭窬?标记的骶髓副交感节前神经元主要分布于同侧中间带外侧核,由它组成的骶髓副交感核在以S2为中心的两个骶髓节段内(有时为三个),形成长约6-10mm的细胞柱。在横切面上,核的中段以上分为位于Ⅶ层外侧缘的外侧带和位于Ⅴ层的背侧带,但在核的尾侧段则二者融合为一。中介核和中间带内侧核也存在少量逆标神经元。示踪剂注于臂旁外侧核或Barrington核(一侧或双侧)后,逆标的盆内脏二级传入神经元主要存在于骶髓中间带外侧核和骶髓后连合核,在中间带外侧核位于两团传出神经元之间的中间带,但在核的尾侧段则位于骶髓副交感核的背外侧部,个别细胞混杂于副交感节前神经元之间,中介核和中间带內侧核也有少量二级传入神经元分布?送?相当数量的盆内脏二级传入神经元位于后角Ⅰ层。本文结果证明猫骶髓中间带外侧核至少由两种不同性质的神经元即骶髓副交感节前神经元和盆内脏二级传入神经元组成,两者在中间带外侧核区有明确的定位分布,因此,可将骶髓中间带外侧核划分为传出亚核和传入亚核,传统上笼统地将骶髓副交感核等同于中间带外侧核是不恰当的。

THE DISTRIBUTION OF EFFERENT AND SECONDARY AFFERENT NEURONS IN THE SACRAL "VISCERAL FIELD" OF THE CAT

The distribution of efferent and secondary afferent neurons in the sacral "visceral field" (dorsal commissural nucleus and bilateral intermediate zone) of the cat have been studied by using a double-labeling technique in which two sensitive retrograde tracers (Fluoro-Gold and HRP) were combined. The parasympathetic preganglionic neurons (PGNs) that were labeled by the tracer injected into the pelvic nerve were identified primarily in the intermediat lateral nucleus (IML) ipsilaterally. They formed a column known as the sacral parasympathetic nucleus (SPN) approximately 6mm-10mm long, usually extended in two, occasionally three, sacral segments. The majority of labeled cells were located in S2, In transverse sections they were distributed among two major components: dorsal band (DB) located mainly in lamina Ⅴ and lateral band (LB) located along the lateral edge of the gray matter in lamina Ⅶ. The interband (IB) between these two populations contained a few or no labeled cells. DB and LB was fused together in the caudal region of the nucleus. Occasionally efferent neurons were found more medially in the intercalated nucleus (IC) and intermediomedial nucleus (IMM), The other tracer applied to the lateral parabrachial nucleus (PBL) or Barrington′s nucleus was detected bilaterally in cells located in the IML, DCN and lamina I of the sacral spinal cord. A few afferent neurons were labeled in the IC and IMM. The secondary afferent neurons in the IML appeared primarily within the interband in the oral and middle region of SPN and dorsolateral to the caudal region of SPN. These findings indicated that the sacral IML in the cat consists of at least two distinct groups of cells, PGNs and visceral secondary afferent neurons that project to the PBL or Barrington′s nucleus. It is improper to name IML as SPN in general.