Romanowski C A, Mitchell I J, Crossman A R
Department of Anatomy, Manchester.
J Anat. 1985 Dec;143:75-95.
The hypothesis that the six cytoarchitectonically distinct subdivisions of the zona incerta send efferent projections to different parts of the brain was tested using retrograde fluorescent tracing techniques. Injections of tracer in the superior colliculus, pontomesencephalic tegmentum, thalamus or spinal cord resulted in characteristic and distinctive patterns of labelling in the zona incerta, suggesting that the different subdivisions of the zona incerta give rise to different sets of efferent projections. Thus, injections into the deep layers of the superior colliculus resulted in retrogradely labelled neurons predominantly in the zona incerta pars ventralis, whereas injections into the pontomesencephalic tegmentum, avoiding the superior colliculus, labelled neurons mostly in the zona incerta pars dorsalis. Parafascicular thalamic injections resulted in labelled neurons in the zona incerta pars rostropolaris, pars dorsalis, pars caudalis and a few in the pars ventralis. The spinal cord injections labelled predominantly the magnocellular cells of the zona incerta. The results of the double labelling experiment also give support to the conclusion that different areas of the zona incerta give rise to largely individual sets of efferent projections. Combined injections of tracers into the superior colliculus and thalamus resulted in the labelling of two essentially independent cell groups, the tectal projecting cells being found mainly in the zona incerta pars ventralis and the thalamic projecting cells being found in the zona incerta pars rostropolaris, pars dorsalis and pars caudalis. However, a small number of double labelled cells was found. These cells, which presumably send collateral projections to both the tectum and the thalamus, were found mainly in the dorsal part of the zona incerta pars ventralis, immediately next to the pars dorsalis. In the light of these findings it would appear that the zona incerta may be organised into largely distinct subdivisions, each of which has its own set of cytoarchitectonic and efferent projection characteristics.
运用逆行荧光追踪技术，对未定带在细胞构筑上明显不同的六个亚区向脑的不同部位发出传出投射这一假说进行了验证。将示踪剂注入上丘、脑桥中脑被盖、丘脑或脊髓后，未定带呈现出特征性且独特的标记模式，这表明未定带的不同亚区会产生不同的传出投射组。因此，注入上丘深层会导致逆行标记的神经元主要集中在未定带腹侧部，而注入脑桥中脑被盖（避开上丘）则标记的神经元大多在未定带背侧部。丘脑束旁核注射导致在未定带嘴极部、背侧部、尾侧部出现标记神经元，腹侧部也有少数。脊髓注射主要标记了未定带的大细胞。双重标记实验结果也支持了这一结论，即未定带的不同区域会产生基本独立的传出投射组。将示踪剂联合注入上丘和丘脑导致标记了两个基本独立的细胞群，投射至上丘的细胞主要见于未定带腹侧部，投射至丘脑的细胞见于未定带嘴极部、背侧部和尾侧部。然而，发现了少量双重标记细胞。这些细胞可能向顶盖和丘脑都发出侧支投射，主要见于未定带腹侧部紧邻背侧部的背侧部分。鉴于这些发现，似乎未定带可能在很大程度上被组织成不同的亚区，每个亚区都有其自身的细胞构筑和传出投射特征。
