Meek J, Hafmans T G, Maler L, Hawkes R
Department of Anatomy and Embryology, University of Nijmegen, The Netherlands.
J Comp Neurol. 1992 Feb 1;316(1):17-31. doi: 10.1002/cne.903160103.
Immunocytochemistry has demonstrated unexpected heterogeneity among cerebellar Purkinje cells. For example, monoclonal antibody Mab anti-zebrin II reveals parasagittal bands of immunoreactive Purkinje cells in the mammalian cerebellum, but reveals a non-sagittal cerebellar compartmentation pattern in goldfish and gymnotiform fish. The present paper investigates the cerebellar compartmentation pattern, as reflected in the zebrin II distribution, in two other teleosts, the electric mormyrid fish Gnathonemus petersii with its large and regularly built gigantocerebellum, and the electrosensory osteoglossomorph teleost Xenomystis nigri, by using light as well as electron microscopic immunohistochemical techniques. Zebrin II is expressed only in Purkinje cells, where it is present in the cytoplasm of all neuronal compartments, including spines, distal and proximal dendrites, the cell body, and the initial part, as well as terminal boutons of the axon. Other types of cerebellar neurons, including the eurydendroid projection neurons, are zebrin II-negative. In Gnathonemus, zebrin II-positive Purkinje cells are present in the large caudolateral part of the valvula, in lobes C2, C3, and C4 of the corpus, and in the anterior as well as the posterior part of the caudal cerebellar lobe. Zebrin II-negative Purkinje cells are present in a continuous region encompassing the rostromedial part of the valvula, the lobus transitorius, lobe C1 and the ventral part of lobe C2, and in a small, lateral zone of the posterior part of the caudal lobe. In Xenomystis, all Purkinje cells, including those in the medial valvula and the posterior part of the caudal lobe, appear to react with mab anti-zebrin II. This more widespread distribution may be due to the presence of a second antigenic polypeptide in this species. On the basis of the present findings, it is concluded that the mormyrid lobus transitorius, lobe C1, and the ventral part of lobe C2 probably belong to the valvula, while the corpus is restricted to the dorsal part of lobe C2, lobe C3, and lobe C4. The functional significance of zebrin II expression for different subsets of teleostean Purkinje cells remains unclear, since comparisons of different teleosts reveal no general correlation with particular afferent or efferent connections, nor with special morphological features such as a dendritic palisade pattern or different arrangements of the Purkinje cell bodies. A comparison between mammals and teleosts suggests that a distinct parasagittal cerebellar zonation in teleosts is absent, and the major part of the teleostean cerebellum may be considered as a single (midsagittal) cerebellar zone, with about the same width as one mammalian parasagittal zone.
免疫细胞化学已证明小脑浦肯野细胞之间存在意想不到的异质性。例如，单克隆抗体抗zebrin II在哺乳动物小脑中显示出免疫反应性浦肯野细胞的矢状旁带，但在金鱼和电鳗形鱼类中显示出非矢状的小脑分区模式。本文通过光镜和电镜免疫组织化学技术，研究了另外两种硬骨鱼——具有大且结构规则的巨大小脑的电鲶Gnathonemus petersii和电感觉骨舌鱼Xenomystis nigri——中zebrin II分布所反映的小脑分区模式。Zebrin II仅在浦肯野细胞中表达，在所有神经元区室的细胞质中都有，包括棘突、远端和近端树突、细胞体、起始部分以及轴突的终末小体。其他类型的小脑神经元，包括广树突投射神经元，则为zebrin II阴性。在Gnathonemus中，zebrin II阳性的浦肯野细胞存在于瓣叶的大尾外侧部分、体部的C2、C3和C4叶以及尾小脑叶的前部和后部。zebrin II阴性的浦肯野细胞存在于一个连续区域，该区域包括瓣叶的吻内侧部分、过渡叶、C1叶和C2叶的腹侧部分，以及尾叶后部的一个小外侧区。在Xenomystis中，所有浦肯野细胞，包括那些在内侧瓣叶和尾叶后部的细胞，似乎都与抗zebrin II单克隆抗体发生反应。这种更广泛的分布可能是由于该物种中存在第二种抗原多肽。基于目前的研究结果，得出结论：电鲶的过渡叶、C1叶和C2叶的腹侧部分可能属于瓣叶，而体部则局限于C2叶、C3叶和C4叶的背侧部分。硬骨鱼浦肯野细胞不同亚群中zebrin II表达的功能意义仍不清楚，因为对不同硬骨鱼的比较显示，它与特定的传入或传出连接、以及特殊的形态特征（如树突栅栏模式或浦肯野细胞体的不同排列）没有普遍相关性。哺乳动物和硬骨鱼之间的比较表明，硬骨鱼中不存在明显的矢状旁小脑分区，硬骨鱼小脑的主要部分可被视为一个单一的（矢状中）小脑区，其宽度与一个哺乳动物矢状旁区大致相同。
