Rodman H R, Karten H J
Department of Neurosciences, University of California, San Diego School of Medicine, La Jolla 92093-0608, USA.
J Comp Neurol. 1995 Aug 28;359(3):424-42. doi: 10.1002/cne.903590306.
A combined immunohistochemical and retrograde tracing approach was used to characterize the catecholaminergic innervation of the optic tectum (TeO), the major target of retinal projections in many avian species. Giemsa counterstaining was employed to determine precisely the laminar localization of immunoreactive fibers and presumptive terminals. The TeO of the pigeon is densely innervated by fibers immunoreactive for tyrosine hydroxylase (TH), which are most heavily distributed to the superficial layers of its dorsal and anterior portions. Within the dorsal-anterior tectum, TH-immunoreactive processes are particularly dense in retinorecipient layers 4 and 7 and in layer 5a. As in the mammalian superior colliculus, the bulk of the catecholaminergic innervation of the pigeon TeO reflects inputs, presumably noradrenergic, originating in the locus coeruleus and nucleus subcoeruleus. However, the catecholaminergic innervation of the pigeon TeO shows several features distinct from those reported for the mammalian superior colliculus. These include an input from a pretectal TH-positive cell group unknown in mammals and the presence of residual TH immunoreactivity after administration of the noradrenergic neurotoxin DSP-4. Moreover, the pattern of TH-immunoreactive fibers in pigeon TeO indicates more laminar and regional specialization within this structure than has been reported for the catecholaminergic innervation of the superior colliculus in mammals.
采用免疫组织化学和逆行追踪相结合的方法，对许多鸟类视网膜投射的主要靶标——视顶盖（TeO）的儿茶酚胺能神经支配进行了表征。使用吉姆萨复染来精确确定免疫反应性纤维和假定终末的层状定位。家鸽的视顶盖密集地接受酪氨酸羟化酶（TH）免疫反应性纤维的支配，这些纤维在其背侧和前部的表层分布最为密集。在背侧前部顶盖内，TH免疫反应性突起在视网膜接受层4和7以及5a层中特别密集。与哺乳动物的上丘一样，家鸽视顶盖的大部分儿茶酚胺能神经支配反映了可能起源于蓝斑和蓝斑下核的输入，推测为去甲肾上腺素能输入。然而，家鸽视顶盖的儿茶酚胺能神经支配表现出一些与哺乳动物上丘报道的特征不同的特点。这些特点包括来自哺乳动物中未知的顶盖前TH阳性细胞群的输入，以及在给予去甲肾上腺素能神经毒素DSP-4后仍存在残余的TH免疫反应性。此外，家鸽视顶盖中TH免疫反应性纤维的模式表明，该结构内的层状和区域特化比哺乳动物上丘的儿茶酚胺能神经支配所报道的更为明显。
