The first volume of the textbook discusses issues of general and comparative embryology. A brief outline of the history of the formation of modern embryology is given, the problems of gametogenesis, fertilization, fragmentation, gastrulation, germ leaves, direct and larval development, metamorphosis are considered. Data on the comparative embryology of sponges, streaks, ctenophores, annelids, mollusks, roundworms, arthropods, echinoderms, tunicates, craneless, lower and higher vertebrates are presented. The textbook is intended for students of biological faculties of universities, teachers of high school biology and everyone interested in embryology problems.