Sanides-Kohlrausch C, Wahle P
Max-Planck Institut für Biophysikalische Chemie, Abt. Neurobiologie, Göttingen, Federal Republic of Germany.
J Comp Neurol. 1990 Jan 15;291(3):468-89. doi: 10.1002/cne.902910312.
The distribution and morphology of Neuropeptide Y-immunoreactive (NPY-ir) neurons in the olfactory bulb and the olfactory peduncle was studied in the adult cat and rat, and the common marmoset Callithrix jacchus. Significant species differences were not observed. In all three species, the population of NPY-ir neurons is localized in the white matter extending from the main olfactory bulb to the border of the striatum. The neurons are characterized by a conspicuously looping axonal ramification pattern with some major collaterals running toward the olfactory bulb and others running toward the internal olfactory tract. The former, ipsilateral projection terminates in the granule cell layer of the main and accessory olfactory bulb and in layer II/III of the anterior olfactory nucleus. Reconstruction of the latter projection has revealed that the fibers are continuous with the olfactory limb of the anterior commissure and the anterior commissure proper suggesting a commissural contralateral projection. The analysis of the postnatal development of the cat NPY neuron system supports this assumption in a very clear-cut way. In young animals growing fibers are observed to cross the brachium of the commissure. The NPY neuron system develops postnatally. The maximum cell number is reached during the third postnatal week. The appearance of more and more NPY-ir neurons slightly precedes the formation of the terminal fields and of the fiber projection in the internal olfactory tract. The density of this early fiber projection by far exceeds the fiber density observed in the adult. Later in development the fiber density in the olfactory limb and the anterior commissure becomes considerably reduced. In contrast, the plexus density in the anterior olfactory nucleus and the granule cell layer of the main and accessory olfactory bulb undergoes only a slight reduction, and the NPY-ir cell number remains roughly constant. These observations suggest that the ipsilateral NPY-ir projection remains largely unchanged, in contrast to the contralateral projection, which exists to a large extent only for the first four postnatal months. The observation that the NPY neuron system gives rise to a contralateral projection does not support a classification of NPY neurons as short axon cells.
在成年猫、大鼠以及普通狨猴（绢毛猴）中研究了嗅球和嗅束中神经肽Y免疫反应性（NPY-ir）神经元的分布和形态。未观察到显著的物种差异。在所有这三个物种中，NPY-ir神经元群体位于从主嗅球延伸至纹状体边界的白质中。这些神经元的特征是具有明显的环状轴突分支模式，一些主要侧支朝向嗅球延伸，另一些则朝向内嗅束延伸。前者，即同侧投射终止于主嗅球和副嗅球的颗粒细胞层以及前嗅核的II/III层。对后者投射的重建显示，纤维与前连合的嗅支和前连合本身相连，提示存在连合对侧投射。对猫NPY神经元系统出生后发育的分析非常明确地支持了这一假设。在幼小动物中，观察到生长的纤维穿过连合臂。NPY神经元系统在出生后发育。出生后第三周达到最大细胞数量。越来越多的NPY-ir神经元的出现略早于内嗅束中终末场和纤维投射的形成。这种早期纤维投射的密度远远超过成年动物中观察到的纤维密度。在发育后期，嗅支和前连合中的纤维密度显著降低。相比之下，前嗅核以及主嗅球和副嗅球颗粒细胞层中的丛密度仅略有降低，并且NPY-ir细胞数量大致保持恒定。这些观察结果表明，与对侧投射不同，同侧NPY-ir投射在很大程度上保持不变，对侧投射在很大程度上仅在出生后的前四个月存在。NPY神经元系统产生对侧投射这一观察结果不支持将NPY神经元归类为短轴突细胞。
