Morphology of the inner ear of mammals in ontogeny

Abstract

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. Unlike the auricle and middle ear, which are characterized by very diverse structural variations and a wide range of adaptive transformations related to the peculiarities of the species ecology, the inner ear of specimens of various ecological groups retains constant structural organization with a wide diversity of functions. In the typical topography of both the cochlear and vestibular analyzers, the form and dimensions of individual components usually vary. The anatomical formation of inner-ear structures is mostly complete in the early prefetal period, whereas the differentiation of cells of the sensory epithelium in the cochlea, macule, and cristae of altricial species continues up to the earliest stages of postnatal ontogenesis. The differentiation of the inner-ear structures in precocial species (cetaceans, ungulate animals) is normally complete by the moment of birth.