Additional file 2: Fig. S1. Representative images of hematoxylin–eosin–stained sections of the sensory epithelium from chicken utricles. (A) Epithelium from a control (saline-injected) chicken. (B) Epithelium from a gentamicin sulfate-injected chicken on day 14 postinjection. Extruded hair cells (arrowheads) and phagocytosis (arrows) are indicated. Fig. S2. Representative images of BrdU incorporation in the utricle as analyzed by immunohistochemistry in control chickens (A) and aminoglycoside-treated chickens on days 2 (B), 7 (C), and 14 (D) after the last gentamicin injection. Fig. S3 Relative expression of the ATOH1 gene. Increased ATOH1 mRNA levels were detected in supporting cells 3 h after aminoglycoside injection and continued for the next 14 days (*p < 0.05)