Alibardi L
Dipartimento di Biologia evoluzionistica sperimentale, University of Bologna, Italy.
Ann Anat. 1998 Oct;180(5):415-26. doi: 10.1016/S0940-9602(98)80102-7.
Neurons in the rat ventral cochlear nucleus which project to the inferior colliculus were identified after retrograde labelling of the neural tracer wheat germ agglutinin conjugated to horse radish peroxidase. After tracer injection into the Inferior Colliculus, electron microscopy and immunocytochemical localization of glycine, GABA and glutamate in retrograde labelled neurons were employed. In the acoustic root area and posterior ventral cochlear nucleus, most of the body surface of the neurons projecting to the inferior colliculus was 10-30% covered by axo-somatic boutons and appeared as multipolar cells of type I. These large to medium size cells with sparse stacks of ergastoplasmic cisternae organized in Nissl bodies, were heavily labelled and were the main projecting neurons to the inferior colliculus. Most of these cells were glycine and GABA negative but variably glutamate positive, suggesting that they are excitatory neurons. This result suggests the absence of an inhibitory innervation of the inferior colliculus from these cells. A few retrograde labelled, large to giant neurons showed an irregular surface, sparse short stacks of ergastoplasmic reticulum, numerous microtubules, cell bodies 60-80% covered by synaptic boutons, and they appeared as multipolar cells of type II. These cells were less strongly retrograde labelled than multipolar type I, and were occasionally glycine positive, presumably inhibitory. This suggests that at least a small caliber collateral axon stemming from these neurons can reach the inferior colliculus. Occasional glycine positive octopus cells not labelled with the tracer were also observed. The contribution of glycinergic axons to the innervation of the inferior colliculus appears therefore to by very limited. Occasional labelled cells were represented by apparently globular bushy neurons, but the weak labelling suggests that the tracer was taken up by collateral axons reaching the inferior colliculus and not by the main axon. Globular bushy cells were consistently negative for both glycine and GABA, and variably positive for glutamate. In the anteroventral cochlear nucleus, labelled multipolar type I and II showed similar immunocytological and ultrastructural characteristics to those in the posteroventral cochlear nucleus but their dimension was smaller. Cells identified as spherical bushy neurons were never retrograde labelled.
通过将与辣根过氧化物酶偶联的神经示踪剂小麦胚凝集素逆行标记后，鉴定出大鼠蜗腹侧核中投射到下丘的神经元。在将示踪剂注入下丘后，采用电子显微镜以及对逆行标记神经元中甘氨酸、γ-氨基丁酸（GABA）和谷氨酸进行免疫细胞化学定位的方法。在听神经根区域和蜗腹侧后核，投射到下丘的神经元的大部分体表被轴体终扣覆盖10%-30%，呈现为I型多极细胞。这些大小为中等至大型的细胞，其尼氏体中有稀疏堆叠的内质网池，被大量标记，是投射到下丘的主要神经元。这些细胞中的大多数对甘氨酸和GABA呈阴性，但对谷氨酸呈不同程度的阳性，表明它们是兴奋性神经元。这一结果表明这些细胞不存在对下丘的抑制性神经支配。少数逆行标记的大至巨型神经元表面不规则，内质网短堆叠稀疏，有大量微管，细胞体被突触终扣覆盖60%-80%，呈现为II型多极细胞。这些细胞的逆行标记强度不如I型多极细胞，偶尔对甘氨酸呈阳性，推测具有抑制性。这表明至少来自这些神经元的一小口径侧支轴突可以到达下丘。还观察到偶尔有未被示踪剂标记的甘氨酸阳性章鱼细胞。因此，甘氨酸能轴突对下丘神经支配的贡献似乎非常有限。偶尔有标记的细胞表现为明显的球状浓密神经元，但标记较弱表明示踪剂是被到达下丘的侧支轴突摄取，而不是被主轴突摄取。球状浓密细胞对甘氨酸和GABA始终呈阴性，对谷氨酸呈不同程度的阳性。在蜗腹侧前核，标记的I型和II型多极细胞显示出与蜗腹侧后核中细胞相似的免疫细胞学和超微结构特征，但尺寸较小。被鉴定为球状浓密神经元的细胞从未被逆行标记。
