Figure 5

Overview of the cephalic nervous system in older N. arenaceodentata juveniles. A-D. Contiguous Z-projections (in order from dorsal-most to ventral-most) of a 9-chaetiger juvenile head. The dashed ellipses in A correspond to cell clusters at the terminal ends of presumed axonal tracts, and thus probably represent posterior brain ganglia. Dashed curves in C indicate roots in the lateral neuropile of presumed tegumentary nerves. Arrowheads in D indicate the roots of the second stomatogastric nerves. E. 13-chaetiger juvenile head. The optical sections comprising this Z-projection (located ventrally in the head) were selected to highlight the distinct paths of cephalic nerves leading to the dorsal and ventral masses of the corpora pedunculata. F. 20-chaetiger juvenile anterior end; nearly full Z-projection showing superficial features. The corpora pedunculata (cp) are evident by their intense nuclear staining. 1st, 2nd parapodia, adc anterodorsal cortex of the brain, ae anterior eye, ag antennal ganglion, an antenna, ann antennal nerve, ant anterior cirrus, cc circumesophageal connective, cp corpora pedunculata, dcp dorsal mass of the corpora pedunculata, drcc dorsal root of cc, gHa? presumed Hamaker's commissural ganglion, gHo? presumed Holmgren's cerebral commissural ganglion, lcr lateral common root of several cephalic nerves, Lo Langdon's organ, nant nerve of anterior cirrus, nc nuchal organ cilia, ndcp nerve of the dcp, ng nuchal ganglion, nLo nerve of Langdon's organ, nn nuchal nerve, np neuropile, nvcp nerve of the vcp, pa palp, pe posterior eye, pn base of axial palp nerve, sgg stomatogastric ganglion, sgn stomatogastric nerve, teLo terminal endings of sensory-cell peripheral processes from Langdon's organ, vcp ventral mass of the corpora pedunculata, vrcc ventral root of cc.