Figure 3

Parapodial innervation and developmental sequence of parapodial processes in N. arenaceodentata. The parapodia shown were isolated from different 13-chaetiger juveniles. Panels A-D are Z-projections of nearly entire parapodia; fluorescent signal from deep structures is muted. Acetylated α-tubulin immunoreactivity is green; labeling of F-actin is red; cell nuclei are blue. Scale bars = 50 μm in A-D; 25 μm in E, F. A. 15th parapodium (pre-chaetigerous), anterior aspect. This Z-projection excludes anterior optical sections that show pn1. B. 13th (youngest chaetigerous) parapodium, anterior aspect. C. 12th parapodium, anterior aspect. D-F. 3rd parapodium, posterior aspect. D. Entire parapodium. E. Close-up of parapodial ganglion; Z-projection of 5 internal optical sections. The putative neuronal growth cone (gc?) is tipped with red F-actin labeling (zoom in to see). F. Close-up of dorsal cirrus. acn acicula-associated nerve, ci ciliary tuft, cn cirrus nerve, dbv dorsal blood vessel, dc dorsal cirrus, dlm dorsal longitudinal muscle, dnl dorsal notopodial ligule, dpm dorsal parapodial muscle, necl neuropodial chaetal lobe, nel neuropodial ligule, nepm neuropodial protractor muscle, nocl notopodial chaetal lobe, om oblique muscle, pg parapodial ganglion, plm parapodial levator muscle, pn1/pn2/pn3 1st/2nd/3rd branch of the parapodial nerve, po/pr post- and pre-chaetal lobes of the neuropodium, sc sensory cilia, vc ventral cirrus, vlm ventral longitudinal muscle, vnc ventral nerve cord, vnl ventral notopodial ligule.