Mitrofanis J, Baker G E
Department of Human Anatomy, University of Oxford, England.
J Comp Neurol. 1993 Dec 22;338(4):575-87. doi: 10.1002/cne.903380407.
This study examines the connections of the thalamic reticular and perireticular nuclei during development. In addition, because these nuclei lie directly in the path of corticofugal and corticopetal axons during development, we have examined the relationship of these growing axons to the reticular and perireticular cell groups. Neurones were labelled by applying DiI, wheat germ agglutinin conjugated to horseradish peroxidase (WGA-HRP), or HRP to the dorsal thalamus and/or cerebral cortex of rats at different stages of development. The axons of neurons in the reticular nucleus reach the dorsal thalamus as early as embryonic day (E) 14. At this age, and during later prenatal development, a small DiI implant limited to the presumptive lateral geniculate nucleus labels reticulothalamic and thalamocortical axons which travel in a clearly defined bundle through the thalamus. During late gestation, thalamocortical (approximately E15) and corticothalamic (approximately E17) axons pass directly through the reticular nucleus toward their targets. It is not until birth that collaterals are seen extending into the nucleus from the parent axons. Neurones in the perireticular nucleus, in contrast to those in the reticular nucleus, are not labelled from the lateral geniculate nucleus until after birth. The perireticular nucleus is very large at a stage when the first thalamocortical axons leave and when the first corticothalamic axons approach the thalamus. These axons are seen to change course sharply in the region of the internal capsule, where there are many perireticular cells. Corticothalamic axons turn toward the reticular nucleus, and thalamocortical axons turn toward the cortical subplate. Corticospinal and corticobulbar axons, on the other hand, pass directly through the perireticular region toward their more caudal targets. After these axons have reached their targets, the perireticular nucleus reduces dramatically in size.
本研究探讨了丘脑网状核和网状旁核在发育过程中的联系。此外，由于在发育过程中这些核直接位于皮质下行和皮质上行轴突的路径上，我们研究了这些生长中的轴突与网状核和网状旁核细胞群的关系。通过将碘化丙啶（DiI）、与辣根过氧化物酶结合的小麦胚凝集素（WGA-HRP）或辣根过氧化物酶（HRP）应用于不同发育阶段大鼠的背侧丘脑和/或大脑皮层来标记神经元。网状核神经元的轴突早在胚胎第14天就到达背侧丘脑。在这个年龄以及随后的产前发育过程中，一个局限于外侧膝状体原基的小DiI植入物标记了网状丘脑和丘脑皮质轴突，它们以明确界定的束状穿过丘脑。在妊娠后期，丘脑皮质（约胚胎第15天）和皮质丘脑（约胚胎第17天）轴突直接穿过网状核朝向它们的靶标。直到出生时，才看到侧支从母轴突延伸到核内。与网状核中的神经元不同，网状旁核中的神经元直到出生后才从外侧膝状体核被标记。在第一批丘脑皮质轴突离开且第一批皮质丘脑轴突接近丘脑的阶段，网状旁核非常大。这些轴突在内囊区域明显改变方向，内囊区域有许多网状旁核细胞。皮质丘脑轴突转向网状核，丘脑皮质轴突转向皮质下板。另一方面，皮质脊髓和皮质延髓轴突直接穿过网状旁区域朝向它们更靠尾侧的靶标。这些轴突到达靶标后，网状旁核的大小急剧减小。
