Lampreys, “Living Fossils,” in Research on Early Development and Regeneration in Vertebrates

Agnathans, the most ancient of the extant vertebrates, evoke steadily increasing interest as the object of research on the basic processes of vertebrate ontogeny. Lampreys have been more accessible to researchers than myxines (hagfish), representatives of the other class of jawless vertebrates, for more than 100 years. Studies on the functional and evolutionary aspects of early ontogeny in lamprey at the molecular level became possible in the past two decades. Studies on the distinctive features of lampreys as the ancient representatives of vertebrates and comparison to gnathostomes, the more modern vertebrates, are of great interest. Molecular studies of lampreys can provide insight into the evolutionary mechanisms for the emergence and development of individual unique structures of vertebrates. The appearance of the telencephalon, which was first detected in lampreys, was one of the most important aromorphoses of vertebrates. Development and advancement of the telencephalon in the course of evolution enabled the implementation of higher forms of nervous activity in vertebrates, including humans. Research on the molecular mechanisms of basic ontogenetic events, such as early embryonic differentiation and neural induction, in the lamprey and other vertebrates is also important. Studies on the well-developed regeneration capacity of lampreys, in turn, give hope for at least partial use of the knowledge gained in future medical practice. This article is a review of recent data on the molecular aspects of the early development of the telencephalon, early embryonic differentiation, and regeneration of lampreys.