Abstract The emergence of the telencephalon as a forebrain part with a complex structure is one of the most important aromorphoses in vertebrate evolution. The telencephalon developed and improved in evolution to allow higher nervous activity forms observed in animals and humans. A telencephalic anlage is separated at the earliest stages of vertebrate ontogenesis, when the anterior part of the neural tube differentiates into three cerebral vesicles: the prozencephalon as an anlage of the future forebrain, the mesencephalon as the future midbrain, and the rhombencephalon as the future hindbrain. The forebrain further differentiates to form the telencephalon and the diencephalon. The development of brain structures and regions is modulated by the expression of certain regulatory genes, which code for transcription factors and signaling molecules. Problems of the evolutionary origin and ontogenesis of the telencephalon are still poorly understood at the molecular level, although they are among central problems of modern developmental biology. Recent studies of the evolutionary mechanisms responsible for the emergence of the telencephalon in vertebrates have paid much attention to cyclostomes (lampreys and hagfishes) as the most evolutionarily ancient vertebrate groups and Tunicata (ascidians) and Cephalochordata (lancelets) as the closest relatives of vertebrates. Cyclostomes are of particular interest because they were the first in evolution to have the telencephalon as a separate morphological structure and because they might preserve the expression patterns and regulatory mechanisms characteristic of vertebrate ancestors. The review summarizes and analyzes the data accumulated in recent years from studies of the genetic mechanisms of early telencephalon development in lower vertebrates and searches for telencephalon homologs in two vertebrate-related chordate groups, Cephalochordata and Tunicata.

中文翻译：

---

端脑早期发育的遗传机制，脊椎动物中枢神经系统的一个独特部分，反映了它的出现和进化

摘要 端脑作为具有复杂结构的前脑部分的出现是脊椎动物进化中最重要的变形之一。端脑在进化中得到发展和改进，以允许在动物和人类中观察到更高的神经活动形式。在脊椎动物个体发育的最早阶段，当神经管的前部分化为三个脑囊泡时，端脑原基被分离出来：前脑作为未来前脑的原位，中脑作为未来的中脑，菱脑作为未来后脑。前脑进一步分化形成端脑和间脑。大脑结构和区域的发育受某些调节基因表达的调节，这些基因编码转录因子和信号分子。端脑的进化起源和个体发育问题在分子水平上仍然知之甚少，尽管它们是现代发育生物学的核心问题之一。最近对负责脊椎动物端脑出现的进化机制的研究非常关注环口动物（七鳃鳗和盲鳗）作为进化最古老的脊椎动物群，而鞘翅目（海鞘）和头脊索动物（柳叶刀）是脊椎动物的近亲。Cyclostomes 特别令人感兴趣，因为它们是进化中第一个将端脑作为单独的形态结构的动物，并且因为它们可能保留脊椎动物祖先的特征表达模式和调节机制。