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Phylogeny of Vertebrates As Seen from Brain Structure

从大脑结构看脊椎动物的系统发育

基本信息

批准号：
60540482
负责人：
TSUNEKI Kazuhiko
金额：
$ 0.9万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1987
项目状态：
已结题

项目摘要

1. Serial sections of the brains of both adults and embryos of various vertebrates were studied histologically. Special attention was paid to the phylogeny and ontogeny of circumventricular organs. Ubiquitously occurring circumbentricular organs in the vertebrate brains are the subcommissural organ and neurohypophysis. The pineal is also found in most species. These fundamental circumventricular organs appear early in ontogeny in most vertebrates. The phylogenetically new organs such as the subfornical organ and area postrema appear late in ontogeny.2. In the course of study of the brain histology, it was revealed that the brain parenchyma of hynobiid salamanders (Hynobius, Pachypalaminus, and Onychodactulus) is not vascularized at all. This is unusual among vertebrate brains. In these salamanders, the ventricle is wide and the neurons are distributed in the periventricular grey. Considering these features together, it may be concluded that the brain of hynobiid salamanders represents the most primitive type of the vertebrate brain.3. The size of nuclei of the cerebellar granular cells was measured in various vertebrates from cyclostomes to mammals. In piscine vertebrates, the size decreases in the following order; Chondrichthyes, Chondrostei, Holostei, and Teleostei. In tetrapods, the size decreases in the following order; Urodela, Aunra, Reptilia, Mammalia, and Aves. The nuclear size represents the genome size. The small nuclear size of teleosts may be related to the evolution under r selection .The large nuclear size of urodeles my be related to the evolution under K selection. Meanwhile, the small nuclear size of birds may be related to their high metabolic activity.

1. 对不同脊椎动物的成人和胚胎的大脑进行了组织学研究。特别注意了心室周围器官的系统发育和个体发育。在脊椎动物大脑中普遍存在的室旁器官是关节下器官和神经垂体。松果体也存在于大多数物种中。这些基本的心室周围器官在大多数脊椎动物的个体发育早期出现。系统发育上的新器官如皮下器官和后发区在个体形成中出现较晚。在脑组织学研究中发现，小鲵（Hynobius、Pachypalaminus和Onychodactulus）的脑实质根本没有血管化。这在脊椎动物的大脑中是不寻常的。在这些蝾螈中，脑室很宽，神经元分布在脑室周围灰质。综合考虑这些特征，可以得出结论：蝾螈的大脑代表了脊椎动物最原始的大脑类型。测量了从环口动物到哺乳动物的各种脊椎动物的小脑颗粒细胞核的大小。在鱼类脊椎动物中，大小按以下顺序递减；软骨鱼、软骨鱼、全骨鱼和硬骨鱼。在四足动物中，大小按以下顺序减小；尾纲动物、爬行动物、哺乳动物和鸟类。核的大小代表了基因组的大小。硬骨鱼的核小可能与r选择下的进化有关。尾虫的大核尺寸可能与K选择下的进化有关。同时，鸟类核的小尺寸可能与它们的高代谢活性有关。