Beitz A J, Shepard R D
J Comp Neurol. 1985 Jul 22;237(4):460-75. doi: 10.1002/cne.902370404.
This study consists of a detailed analysis of neurons in the midbrain periaqueductal gray of the rat utilizing four variants of the Golgi technique. Neurons were classified into three major categories based on soma shape, number of primary dendrites, number of dendritic bifurcations, interspinous distance, axonal origin, and axon trajectory. Neurons in each category were further subdivided into large and small varieties based predominantly on soma size and dendritic patterns. Both quantitative and qualitative data concerning each neuronal type is provided as well as data relating to its relative distribution among the four periaqueductal gray subdivisions. The small bipolar neuron, characterized by its small size and spindle-shaped soma, was the most prominent cell type observed, composing 37% of the impregnated neurons in our material. This cell type was most numerous in the medial subdivision and least prominent in the dorsolateral subdivision. The small triangular neuron composed 23% of the neuronal population and was relatively evenly distributed through the periaqueductal gray. The remaining four cell types include the large and small multipolar neurons, the large fusiform neurons, and the large triangular neurons. Axons originated from either the perikaryon or a proximal dendrite, with a dendritic origin being most common for large and small triangular neurons and large fusiform neurons. The trajectory of axons in single thick coronal sections originating from periaqueductal gray neurons is typically away from the mesencephalic aqueduct. The exact trajectory is dependent on the location of the neuron. Axons arising from cells in the dorsal subdivision usually project in a dorsal or dorsolateral direction while axons of ventrolateral neurons may project dorsally, laterally, or ventrally. In sum, these data indicate a complex level of internal organization of the periaqueductal gray. The results are discussed in terms of previous immunohistochemical studies of neurons in this region.
本研究利用高尔基技术的四种变体，对大鼠中脑导水管周围灰质中的神经元进行了详细分析。根据细胞体形状、初级树突数量、树突分支数量、棘间距离、轴突起源和轴突轨迹，将神经元分为三大类。每一类中的神经元又主要根据细胞体大小和树突模式进一步细分为大、小两种类型。提供了有关每种神经元类型的定量和定性数据，以及其在导水管周围灰质四个亚区中的相对分布数据。小型双极神经元以其小尺寸和纺锤形细胞体为特征，是观察到的最突出的细胞类型，占我们材料中浸染神经元的37%。这种细胞类型在内侧亚区数量最多，在背外侧亚区最不突出。小型三角神经元占神经元总数的23%，相对均匀地分布在导水管周围灰质中。其余四种细胞类型包括大、小多极神经元、大型梭形神经元和大型三角神经元。轴突起源于胞体或近端树突，对于大型和小型三角神经元以及大型梭形神经元来说，树突起源最为常见。源自导水管周围灰质神经元的单个厚冠状切片中的轴突轨迹通常远离中脑导水管。确切轨迹取决于神经元的位置。源自背侧亚区细胞的轴突通常向背侧或背外侧投射，而腹外侧神经元的轴突可能向背侧、外侧或腹侧投射。总之，这些数据表明导水管周围灰质的内部组织水平复杂。根据该区域先前的神经元免疫组织化学研究对结果进行了讨论。
