Voigt T, de Lima A D
Max-Planck-Institut für Entwicklungsbiologie, Tübingen, Germany.
J Comp Neurol. 1991 Dec 8;314(2):403-14. doi: 10.1002/cne.903140214.
We have investigated the serotoninergic innervation of the adult ferret cerebral cortex with immunohistochemical techniques. Distribution pattern of serotoninergic fibers in the ferret neocortex is characterized by a decrease in the density of fibers as one moves from the pial surface towards the white matter. Throughout the entire cerebral cortex, the serotoninergic fibers are very dense within the supragranular layers, especially within layer 1. In contrast, granular and infragranular layers exhibit only a sparse innervation. Although this general pattern of innervation is roughly the same in all cortical areas, significant variations in the fiber density are apparent in different regions. Areas 17, 1, 6, and 8 (primary visual cortex, presumptive somatosensory cortex, presumptive motor cortex, and prefrontal cortex, respectively) are described in more detail to illustrate the diversity of the serotoninergic innervation patterns. The density of innervation is highest in areas 1 and 6, intermediate in area 8, and lowest in area 17. It is noteworthy that while areas 1, 6, and 8 show a marked decrease in fiber density at the boundary between layer 3 and 4, the less strongly innervated area 17 shows a change in density in the transition from layer 2 to layer 3. The types of fibers found within the ferret cortex are similar to those described in other mammalian species. The bulk of the innervation is made by very fine fusiform axons with small ovoid varicosities. In addition to this fiber type, axons with thick round varicosities and some smooth nonvaricose axons were found. The latter types occur in very small numbers within the supragranular layers and mostly in more anterior cortical regions. While the general innervation pattern and the fiber types are similar to those described in the cat cerebral cortex, the pericellular baskets found in the cat cortex (Mulligan and Törk, J Comp Neurol 270:86-110, 1988) are not seen in the ferret.
我们运用免疫组化技术研究了成年雪貂大脑皮质的5-羟色胺能神经支配。雪貂新皮质中5-羟色胺能纤维的分布模式特点是，从软膜表面向白质移动时纤维密度降低。在整个大脑皮质中，5-羟色胺能纤维在颗粒上层内非常密集，尤其是在第1层内。相比之下，颗粒层和颗粒下层仅表现出稀疏的神经支配。尽管这种总体的神经支配模式在所有皮质区域大致相同，但不同区域的纤维密度存在明显差异。为说明5-羟色胺能神经支配模式的多样性，对17区、1区、6区和8区（分别为初级视觉皮质、推测的躯体感觉皮质、推测的运动皮质和前额叶皮质）进行了更详细的描述。神经支配密度在1区和6区最高，在8区居中，在17区最低。值得注意的是，虽然1区、6区和8区在第3层和第4层之间的边界处纤维密度显著降低，但神经支配较弱的17区在从第2层过渡到第3层时密度发生了变化。雪貂皮质内发现的纤维类型与其他哺乳动物物种中描述的相似。大部分神经支配由具有小卵形膨体的非常细的梭形轴突构成。除了这种纤维类型外，还发现了具有厚圆形膨体的轴突和一些光滑无膨体的轴突。后一种类型在颗粒上层内数量非常少，且大多出现在更靠前的皮质区域。虽然总体神经支配模式和纤维类型与猫大脑皮质中描述的相似，但在雪貂中未见到猫皮质中发现的细胞周围篮状结构（Mulligan和Törk，《比较神经学杂志》270:86 - 110，1988）。
