Adaptation of the In Situ Hybridization Method for Working with Embryos and Larvae of Modern Representatives of Phylogenetically Ancient Groups of Vertebrates: Lampreys, Cartilaginous Fishes and Sturgeons

Studies of the temporal and spatial features of expression of regulatory genes in modern representatives of phylogenetically important evolutionarily ancient groups of vertebrates can be very informative for identifying the molecular mechanisms underlying the emergence of new structures and morphological features in ancestral vertebrates. One of the key methods for visualizing regions of active gene transcription is the in situ hybridization method widely used in many traditional model objects, including vertebrates. In this article, the authors describe the successful adaptation of this method to such nonstandard objects as embryos and larvae of lampreys, sharks, and sturgeons and provide protocols for hybridization with these objects.