[The middle ear in the ontogenesis of mammals].

The middle ear in mammals is characterized by structural variations and a broad spectrum of adaptive transformations related to peculiarities of species ecology, but it preserves the general basic principle of structure in most mammals. In species remote from a phylogenetic point of view but close in ecologic specialization, features of parallelism are observed concerning the development of separate elements of auditory ossicles as well as the way of their interconnection and attachment to the tympanic cavity. Along the way to the adaptation to the water lifestyle in semi-aqueous and aqueous species, new additional structures, not intrinsic to initial terrestrial forms, have been formed.

[Inner ears (auris interna) of mammals in ontogenesis].

In both phylogenesis and ontogenesis, the inner ear is formed first as a core, which, phylogenetically, is the most ancient part of the peripheral region of the auditory system. Along with the development of the inner ear, other links of different evolutionary ages (the auricle is a phylogenetically young link) begin to form in the peripheral auditory system.

[Organs of hearing and equilibrium during ontogenesis of mammals].

The peripheral part of acoustic analyzer was studied during pre- and postnatal development of mammals. The main trends of structural evolution of the outer, middle, and inner ear were followed in representatives of different ecological groups during postnatal development. The use of ecologomorphological approach made it possible to establish that specific structural features of the hearing organ in different mammals are determined by adaptation to specific acoustic properties of the environment.