Table 1 Serotonin-like immunoreactive neurons in walking leg ganglia of the investigated pycnogonid species
SL-ir neuron type | Pycnogonum litorale (N = 7) | Meridionale sp. (N= 3) | Cilunculus japonicus (N = 6) | |||
|---|---|---|---|---|---|---|
Abbreviation | Soma position | Primary neurite | Neurite course & morphology | No. & Comments | No. & Comments | No. & Comments |
DMN | medial, dorsal | contralateral | extensive arborizations in contralateral hemiganglion | WLG1: 1 large DMN | WLG1: 1 large DMN | WLG1: 1 large DMN |
WLG2-4: 2 large DMNs; | WLG2-4: 1 large, 1 small DMN; | WLG2-4: 1 large, 1 small DMN; | ||||
strong SLI | strong SLI | strong SLI | ||||
cAMN | antero-medial, ventral | contralateral | contributes to median SL-ir domain + projects into contralateral connective | WLG1-4: 1 cAMN; strong SLI; | WLG1-4: 1 cAMN; strong SLI | WLG1-4: 1 cAMN; strong SLI |
bipolar in some WLGs of 3 specimens | ||||||
iAMN | antero-medial, ventral to dorsal | ipsilateral | projects far laterally along anterior margin of ipsilateral SL-ir domain | WLG1-4: 2v iAMNs; strong SLI | WLG1: 2v + 1 iAMNs | WLG1: 2v + 1 iAMNs |
WLG2-4: 2v + 2 iAMNs; | WLG2-4: 2v + 2 iAMNs; | |||||
strong SLI | strong SLI | |||||
ALN | antero-lateral, ventral to dorsal | ipsilateral | projects posteriorly into ipsilateral SL-ir domain | WLG1-4: 5–14 iAMNs; | WLG1: 1d ALN | WLG1: 1-2v & 1d ALNs |
typically ~10 neurons from v to d; | WLG2-4: 0-2v & 1 or 2d ALNs; | WLG2-4: 1-2v & 1-2d ALNs; | ||||
varying intensity of SLI | vALNs low SLI | vALNs low SLI | ||||
PLN | postero-lateral, central to dorsal | ipsilateral | projects anteriorly into ipsilateral SL-ir domain | WLG1: 0 or 1 PLNs | WLG1&4: 1 or 2 PLNs | WLG1&2: 1 or 2 PLNs |
WLG2-4: 0–2 PLNs | WLG2&3: 2 PLNs; | WLG3&4: (0 or) 1 PLN | ||||
if 2 PLNs, 1 often lower SLI | if 2 PLNs, 1 often lower SLI | if 2 PLNs, 1 often lower SLI | ||||
VMN | medial, far ventral | ipsilateral | projects postero-laterally into postero-medial region of ipsilateral SL-ir domain | WLG1-4: 0 or 1 VMN; low SLI | WLG1-4: 0 or 1 VMN; low SLI | WLG1-4: 1VMN, low SLI |
PVN | postero-medial, ventral | ipsilateral | extends anteriorly into postero-medial region of ipsilateral SL-ir domain | WLG1-4: 0–2 PVNs; low SLI | WLG1-4: − | WLG1-4: 1 or 2 PVNs; low SLI |