Mitani A, Ito K, Mitani Y, McCarley R W
Department of Psychiatry, Harvard Medical School, Brockton, Massachusetts 02401.
J Comp Neurol. 1988 Aug 15;274(3):371-86. doi: 10.1002/cne.902740307.
There are three different descending projections from the bulbar gigantocellular tegmental field (BFTG) in the cat, as defined by intracellular recording and intracellular horseradish peroxidase (HRP) techniques. The first pathway arises from neurons which send axons to the contralateral medial longitudinal fasciculus (cMLF neurons); cMLF neurons show excitatory postsynaptic potentials (EPSPs) after stimulation of the ipsilateral pontine gigantocellular tegmental field (PFTG). Most cMLF neurons have large ellipsoid-polygonal somata (mean, 56.8 micron), thick axons (average diameter, 3.09 microns), mostly non-spiny dendrites and dendritic fields flattened in the anteroposterior direction. No cMLF neurons with axon collaterals in the BFTG are present in the data of this study. The second pathway arises from neurons which send axons to the ipsilateral MLF (iMLF neurons); iMLF neurons show EPSPs after stimulation of the ipsilateral PFTG. Most iMLF neurons have large ellipsoid-polygonal somata (mean, 60.2 microns), thick axons (average diameter, 3.00 microns), mostly non-spiny dendrites and dendritic fields that are only slightly flattened in the anteroposterior direction. As with cMLF neurons, no iMLF neurons with axon collaterals in the BFTG are present in the data of this study. The third pathway arises from neurons that send axons directly into the ipsilateral caudal bulbar reticular formation (iBRF neurons). Most iBRF neurons have smaller ellipsoid-polygonal somata (mean, 38.6 microns), thinner axons (average diameter, 1.84 microns), mostly nonspiny dendrites, and dendritic fields that are flattened in the anteroposterior direction. In contrast to cMLF and iMLF neurons, axon collaterals are present in 73% of iBRF neurons. About half of iBRF neurons have bifurcated axon collaterals with both anterior and posterior projections, and in these neurons antidromic spike potentials are elicited by stimulation of the ipsilateral PFTG.
根据细胞内记录和细胞内辣根过氧化物酶（HRP）技术的定义，猫的延髓巨细胞被盖区（BFTG）存在三种不同的下行投射。第一条通路起源于将轴突发送到对侧内侧纵束的神经元（cMLF神经元）；刺激同侧脑桥巨细胞被盖区（PFTG）后，cMLF神经元显示出兴奋性突触后电位（EPSP）。大多数cMLF神经元具有大的椭圆形-多边形胞体（平均56.8微米）、粗轴突（平均直径3.09微米）、大多无棘的树突以及在前后方向扁平的树突野。本研究的数据中不存在在BFTG中有轴突侧支的cMLF神经元。第二条通路起源于将轴突发送到同侧内侧纵束的神经元（iMLF神经元）；刺激同侧PFTG后，iMLF神经元显示出EPSP。大多数iMLF神经元具有大的椭圆形-多边形胞体（平均60.2微米）、粗轴突（平均直径3.00微米）、大多无棘的树突以及仅在前后方向略有扁平的树突野。与cMLF神经元一样，本研究的数据中不存在在BFTG中有轴突侧支的iMLF神经元。第三条通路起源于将轴突直接发送到同侧延髓尾侧网状结构的神经元（iBRF神经元）。大多数iBRF神经元具有较小的椭圆形-多边形胞体（平均38.6微米）、较细的轴突（平均直径1.84微米）、大多无棘的树突以及在前后方向扁平的树突野。与cMLF和iMLF神经元不同，73%的iBRF神经元存在轴突侧支。大约一半的iBRF神经元具有分叉的轴突侧支，既有向前投射也有向后投射，并且在这些神经元中，刺激同侧PFTG可引发逆向动作电位。
