Otic vesicle constricts to form the canalis reuniens. The central part of the otic vesicle represents the membranous vestibule, and is subdivided by a constriction into a smaller ventral part, the saccule, and a larger dorsal and posterior part, the utricle. The dorsal component of the inner ear also consists of what will become the semicircular canals. The utricle and saccule communicate with each other by means of a Y-shaped canal. The FGF, Bmp, Wnt and Pax genes are likely to be involved in otic induction. FGF and BMP signals help control patterning in the early otic vesicle. Fgf3 and Fgf10 are
Otic notch it did not function in transmitting low-energy vibrations, thus rendering these animals effectively deaf to airborne sound. The otic notch instead functioned as a spiracle, at least in the early forms. Otic notch Otic notches are invaginations in the posterior margin of the skull roof, one behind each orbit. Such notches are found in labyrinthodonts and some of their immediate ancestors, but not in their reptilian descendants. The presence or absence of the otic notches is one of the traits used to separate the amniotes from the amphibian grade tetrapods. The notches have been interpreted as part of an auditory