Fig. 2

Gross anatomy of the adult VNC of four studied species. Immunolabeling of acetylated tubulin (white) with nuclear counterstain (blue), maximum projections of vibratome sections (a, b) or wholemount VNCs (c). Asterisks mark fused vestiges of the transient posterior ganglion anlagen. a P. litorale, sagittal section of first juvenile instar, anterior to the left. Note the inclusion of walking leg neuromere 1 in the subesophageal ganglion. b Meridionale sp., sagittal section of adult male, anterior to the left. Note the distinct anatomical separation of the subesophageal ganglion and the one of walking leg segment 1. c Adult VNC of C. brevirostris (left) and T. orbiculare (right), ventral view. Note anatomical separation of the subesophageal ganglion and walking leg ganglion 1 in C. brevirostris, but their fusion in the antero-posteriorly compressed VNC of T. orbiculare. Arrowheads highlight the ventral longitudinal tracts that are particularly conspicuous in the left VNC. Abbreviations: br – brain, eso – esophagus, mg – midgut, ot – ocular tubercle, ovn – ovigeral neuromere, pan – palpal neuromere, pha – pharynx, seg – subesophageal ganglion, wlg – walking leg ganglion, wln – walking leg neuromere