Structure of the swim bladder pad in E. maculatus shown in transverse semithin sections (A-B) and as a three-dimensional reconstruction (C). The swim bladder pad is composed of four components: (1) parts of the swim bladder wall (white arrowheads), (2) connective material (cm, light blue) dorsally and laterally attaching the swim bladder extension to the skull, (3) connective material in the ventral portion of the pad (black arrowheads), and (4) connective material (limited by dashed lines and shown in dark green) in the ventro-medial part of the pad. bv, blood vessel; cm, connective material; N, nerve; ms, macula sacculi; PLLN, posterior lateral line nerve; prec, recessus situated posterior to the utricle; sac, saccule; VIII, ocataval nerve; (?)IX/X, glossopharyngeal and vagal nerves. Scale bars, 500 μm.