Morphological studies of marginal nuclei in chicken spinal cord.

边缘核(MN)由3个亚核组成，即大核(Mj)、小核(Mn)和腹侧核(V)。我们在光学显微镜和电子显微镜下观察到边缘核。MN呈节段性分布于侧柱。MJ由白质和投射部分组成，相邻的白质部分在分布上部分重叠。Mn和Mj的神经元平均大小中等，V的神经元较大。尼氏物质的出现与神经元的大小有关。小型神经元包括几个相互分离的尼氏物质小簇。中型神经元胞浆内含有大量的核糖体和游离核糖体，这些核糖体由尼氏物质组成，但尼氏物质没有形成簇状或块状。在大型神经元中，尼氏物质呈大块状，彼此分离。根据突触小泡的形状划分其体细胞上的突触前突触和边缘核神经元的树突。有4种类型的突触前…TIC较多，以透明球形小泡为特征的S型，以透明球形小泡加颗粒状小泡为特征的SG型，以透明球形小泡加透明扁平小泡为特征的SF型，以上述3种小泡为特征的SFG型。S类型出现频率最高。根据形态特征，我们认为Mn和Mj可能具有相同的功能意义，但不同于V。白质和Mj的投射部分可能具有相同的功能意义。MJ和V含有大量含糖原的星形胶质细胞。这些含糖原星形胶质细胞的结构从糖原小体细胞到纤维性星形胶质细胞不等。Mn和Mj的星形胶质细胞突起较少，脑池明显扩张。颈髓MN神经元的轴突终止于颈膨大下方的不同节段，颈髓MN神经元的轴突终止于腰骶部以上各节段的尾侧节段

Marginal nuclei (MN) consist of 3 subnuclei, major (Mj), minor (Mn) and ventral (V) marginal nuclei. We observed light and electron microscopically marginal nuclei. Mn were segmentally located in the lateral column. Mj consisted of the white matter and projected parts and the adjoining white matter parts overlaped partly in distribution. Neurons in Mn and Mj were medium in mean size and in V were large. Appearance of Nissle substances correlated with the size of neurons. Small-sized neurons included a few small clusters of nissle substance separated from one another. Cytoplasm of medium-sized neurons included plenty of rER and free ribosomes that consist of Nissle substance but the Nissle substance did not form cluster or block. In large-sized neurons Nissle substance had the form of large blocks separated from one another.Presynaptic boutons on their somata and dendrites of marginal nuclei neurons were divided according to the shape of synaptic vesicles. There were 4 types of presynap … More tic boutons, S type characterized by clear and spherical vesicles, SG type characterized by clear and spherical vesicles plus granular vesicles, SF type characterized by clear and spherical vesicles plus clear and flattened vesicles, and SFG type characterized by the above mentioned 3 types of vesicles. S type occurred most frequently. There were not significant differences in the frequency of these type of presynaptic boutons among the subnuclei.Based on the morphology, we suggested that Mn and Mj may be the same functional significance but different from V.The white matter and projected parts of Mj may be the same functional significance.Astrocytes in MN had pecliar structures. Mj and V included a large amount of glycogen containing astrocytes. These glycogen containing astrocytes ranged in structure from glycogen body cells to fibrous astrocytes. Astorocytes with a few processes and markedly dilated cisterns of rER distributed in Mn and Mj. Although Mn appeared to be gray matter, astrocytes in Mn were fibrous type.Axons of MN neurons in the lumbosacral intumescence terminated in the rostral various levels below the cervical intumescence and axons of MN neurons in the cervical one terminated in the various caudal levels above the lumbosacral one Less