Fig. 1

Histological overview of the rhinophore of Archidoris pseudoargus. a-e: Two sagittal (a, b) and three frontal (c-e) Mallory-stained sections at different planes of the rhinophore. The locations of the frontal sections are indicated in a. The rhinophore ganglion (RG) extends along the entire rhinophore and has side branches (SB) projecting to the rhinophore lobes (RL). A large central lymphatic channel (LC) is located close to the RG (b-e). In two sagittal sections f, g the projection of the side branch (SB) and a bifurcation of the lymphatic channel into the RL is shown. The epidermal cells of the RL possess cilia (C). h, i: Frontal sections of the nervous tissue in the ganglion. Higher magnification of the RG (h) with side branches (i), a glia-like sheath (arrow), different types of cell bodies (CB1 and CB2) and stained neurofilament (NF). Cross-section of fibres (circle). Scale bar: a-e = 500 μm, f, g = 100 μm, h, i = 25 μm