Engbretson G A, Brecha N, Reiner A
Cell Tissue Res. 1982;227(3):543-54. doi: 10.1007/BF00204784.
We examined the parietal eye visual system of the iguanid lizard Uta stansburiana for the presence of substance P-like immunoreactivity by use of both immunofluorescence and peroxidase-antiperoxidase techniques. In the parietal eye no substance P-containing somata were found; however, its plexiform layer contained small (ca. 1 micron diam) immunoreactive fibers. These fibers apparently originate outside the parietal eye. Immunoreactive fibers also were found in the parietal nerve, the dorsal sac, and the leptomeninx of the pineal gland. No labeled somata were observed in any of these regions in either normal or colchicine treated animals. Previously we demonstrated that a system of centrifugal fibers to the parietal eye originates from neurons in the dorsal sac (Engbretson et al. 1981). The apparent absence of substance P-containing neurons in the dorsal sac suggests that the substance P-containing fibers in the parietal eye are not the previously observed centrifugal fibers. The source of the substance P-containing fibers in the parietal eye is unknown. The pars dorsolateralis of the left medial habenular nucleus receives a dense substance P-positive projection. No such projection was seen in the right habenula. Simultaneous visualization of the terminals of ganglion cells of the parietal eye (labeled with orthograde intraaxonally transported horseradish peroxidase) and substance P-like immunofluorescence showed that the locus of habenular immunoreactivity is distinct from the projection field of the parietal eye. Thus the substance P-positive terminals in the habenula do not originate in the parietal eye. Transection of the parietal nerve confirmed this conclusion.
我们运用免疫荧光和过氧化物酶-抗过氧化物酶技术，检查了变色蜥属蜥蜴斯坦氏强棱蜥的顶眼视觉系统，以确定是否存在P物质样免疫反应性。在顶眼中未发现含有P物质的胞体；然而，其神经纤维层含有小的（直径约1微米）免疫反应性纤维。这些纤维显然起源于顶眼之外。在顶神经、背囊和松果体的软脑膜中也发现了免疫反应性纤维。在正常动物或秋水仙碱处理的动物中，在这些区域均未观察到标记的胞体。此前我们证明，一条通向顶眼的离心纤维系统起源于背囊中的神经元（恩布雷特森等人，1981年）。背囊中明显不存在含有P物质的神经元，这表明顶眼中含有P物质的纤维不是先前观察到的离心纤维。顶眼中含有P物质的纤维来源不明。左侧内侧缰核的背外侧部接受密集的P物质阳性投射。在右侧缰核中未见到这样的投射。同时观察顶眼神经节细胞的终末（用顺行轴内运输的辣根过氧化物酶标记）和P物质样免疫荧光显示，缰核免疫反应性的位点与顶眼的投射区域不同。因此，缰核中P物质阳性终末并非起源于顶眼。切断顶神经证实了这一结论。
