Fig. 4

A Light micrograph of a transverse section of Bathochordaeus stygius’ oral region displaying the dorsal mouth opening with the lateral sensory organ on the right side of the mouth (mo). B Light micrograph of the lateral right oral sensory organ with frames highlighting the cilia, the epidermal cells, and the neurites enlarged in (C, D, and E). C Bundle of cilia (ci) emerging between epidermis cells. White arrowheads point to cell contacts. Black arrows point at apical dark areas probably (questionmarks: possibly) rootlets of cilia. D Neurites (ne) contacting the sensory cells (double arrowheads). E Apical part of epidermis cells with intracellular matrix (icm). aj—apical junctions, ec—epidermis cell, en—endostyle, ep—epidermis, hr—house rudiment, icm—intracellular matrix, ne—neurites, nu—nucleus, sc—sensory cell