Puzdrowski R L
Department of Biology, University of Michigan, Ann Arbor 48109.
J Morphol. 1988 Nov;198(2):131-47. doi: 10.1002/jmor.1051980202.
The horseradish peroxidase (HRP) histochemical technique was used to examine the peripheral distribution and afferent projections of the trigeminal nerve in the goldfish, Carassius auratus. Sensory fibers of the trigeminal nerve distribute over the head via four branches. The ophthalmic branch distributes fibers to the region above the eye and naris. The maxillary and mandibular branches innervate the regions of the upper and lower lip, respectively. A fourth branch of the trigeminal nerve was demonstrated to be present in the hyomandibular trunk. Upon entering the medulla the trigeminal afferent fibers divide into a rostromedially directed bundle and a caudally directed bundle. The rostromedially directed bundle terminates in the sensory trigeminal nucleus (STN) located within the rostral medulla. The majority of fibers turn caudally, forming the descending trigeminal tract. Fibers of the descending trigeminal tract terminate within three medullary nuclei: the nucleus of the descending trigeminal tract (NDTV), the spinal trigeminal nucleus (Spv), and the medial funicular nucleus (MFn). All projections, except for those to the MFn, are ipsilateral. Contralateral projections were observed at the level of the MFn following the labeling of the ophthalmic and maxillomandibular branches. All branches of the trigeminal nerve project to all four of the trigeminal medullary nuclei. Projections to the STN and MFn were found to be topographically organized such that the afferents of the ophthalmic branch project onto the ventral portion of these nuclei, while the afferents of the maxillo- and hyomandibular branches project to the dorsal portion of these nuclei. Cells of the mesencephalic trigeminal nucleus were retrogradely labeled following HRP application to the ophthalmic, maxillary, and mandibular branches of the trigeminal nerve. In addition to demonstrating the ascending mesencephalic trigeminal root fibers, HRP application to the above-mentioned branches also revealed descending mesencephalic trigeminal fibers. The descending mesencephalic trigeminal fibers course caudally medial to the branchiomeric motor column and terminate in the ventromedial portion of the MFn.
采用辣根过氧化物酶（HRP）组织化学技术研究了金鱼（Carassius auratus）三叉神经的外周分布及传入投射。三叉神经的感觉纤维通过四个分支分布于头部。眼神经分支将纤维分布到眼和鼻孔上方区域。上颌神经和下颌神经分支分别支配上唇和下唇区域。已证实三叉神经的第四个分支存在于舌颌干中。进入延髓后，三叉神经传入纤维分为一束向吻内侧走行的纤维束和一束向尾侧走行的纤维束。向吻内侧走行的纤维束终止于位于吻侧延髓内的三叉神经感觉核（STN）。大多数纤维转向尾侧，形成三叉神经下行束。三叉神经下行束的纤维终止于三个延髓核：三叉神经下行束核（NDTV）、三叉神经脊束核（Spv）和内侧索核（MFn）。除了投射到MFn的纤维外，所有投射均为同侧。在标记眼神经和上颌下颌神经分支后，在MFn水平观察到对侧投射。三叉神经的所有分支均投射到所有四个三叉神经延髓核。发现投射到STN和MFn的纤维呈拓扑组织，使得眼神经分支的传入纤维投射到这些核的腹侧部分，而上颌神经和舌颌神经分支的传入纤维投射到这些核的背侧部分。在将HRP应用于三叉神经的眼神经、上颌神经和下颌神经分支后，中脑三叉神经核的细胞被逆行标记。除了显示中脑三叉神经上升根纤维外，将HRP应用于上述分支还揭示了中脑三叉神经下降纤维。中脑三叉神经下降纤维向尾内侧走行于鳃弓运动柱的内侧，并终止于MFn的腹内侧部分。
