This volume is inspired by the traditions of the oldest biology department in Russia, named after the academician E.N. Pavlovsky, which recently turned 210 years old. Comparative anatomy has been taught at the department since the time of K. Baer, who discovered the mammalian egg and introduced the teaching of comparative anatomy and embryology. The materials presented here will be useful to medical students learning the comparative anatomy of organs and systems, as well as high school students of biology. The book will provide the reader with a better understanding of phylogenetically determined anomalies and malformations of the development of internal organs in humans.