Norita M
J Comp Neurol. 1980 Mar 1;190(1):29-48. doi: 10.1002/cne.901900104.
Golgi and electron microscopic observations were made on the neurons in the deep layers (below the stratum opticum) of the cat superior colliculus. Large neurons, 35-60 micrometers in somal diameter, occur mainly in the lateral two-thirds of the colliculus. They have numerous somatic and dendritic spines and receive a large number of axon terminals (bouton covering ratio: more than 70%). The medium-sized neurons (20-30 micrometer), with a moderate number of dendritic spines, show a lower bouton covering ratio (25-30%). The ratio for small neurons (8-15 micrometers), with very few dendritic spines, is less than 10%. The medium-sized and small neurons are distributed throughout the colliculus and show marked variability in the dendritic arrangement. Seven different types of axon terminals were distinguished: types I, II, V, and VII form asymmetrical and types III, IV, and VI symmetrical synapses. Type I terminals represent small boutons containing predominantly spherical vesicles, and are in contact mainly with small dendritic profiles. Type II terminals are medium-sized and slender, contain a mixture of spherical and slightly oval vesicles, and make synaptic contacts with small to medium-sized dendrites and somatic spines. This type of terminal is occasionally presynaptic to vesicle-containing dendrites (type VIII). Type III terminals are small, contain flattened vesicles predominantly, and are presynaptic to a wide variety of neuronal elements in the deep layers of the superior colliculus. Type IV terminals are represented by medium to large-sized boutons that contain pleomorphic vesicles and make synaptic contacts chiefly with the large neurons. Type V and VI terminals exhibit a quite dense axoplasmic matrix and mainly contact the large neurons. Type VII terminals are often in the form of boutons en passant and contain numerous large granular vesicles. Pleomorphic vesicle-containing dendrites (type VIII terminals) are also observed to participate in the axodendrodendritic serial synapses.
对猫上丘深层（视层以下）的神经元进行了高尔基染色和电子显微镜观察。大神经元，胞体直径为35 - 60微米，主要出现在丘的外侧三分之二区域。它们有许多胞体和树突棘，并接受大量轴突终末（终末覆盖率：超过70%）。中等大小的神经元（20 - 30微米），树突棘数量适中，终末覆盖率较低（25 - 30%）。小神经元（8 - 15微米）树突棘极少，其比例小于10%。中等大小和小的神经元分布于整个丘，其树突排列表现出明显的变异性。区分出七种不同类型的轴突终末：I型、II型、V型和VII型形成不对称突触，III型、IV型和VI型形成对称突触。I型终末代表主要含有球形囊泡的小终扣，主要与小的树突轮廓接触。II型终末中等大小且细长，含有球形和稍椭圆形囊泡的混合物，并与小到中等大小的树突和胞体棘形成突触联系。这种终末偶尔在含囊泡的树突（VIII型）前形成突触。III型终末小，主要含有扁平囊泡，在上丘深层与多种神经元成分形成突触前联系。IV型终末由含有多形性囊泡的中等大小到大型终扣代表，主要与大神经元形成突触联系。V型和VI型终末表现出相当致密的轴浆基质，主要与大神经元接触。VII型终末常呈串珠状终扣形式，含有许多大颗粒囊泡。还观察到含多形性囊泡的树突（VIII型终末）参与轴 - 树 - 树突连续突触。
