Table 1 The nerve elements of phoronid larvae and their fate during metamorphosis
Name of nerve element (labelled in Figure1C) | Expression of 5HT | Expression of FMRFamide | Expression of alfa-tubulin | Fate during metamorphosis and (immunoreactivity in juveniles) |
|---|---|---|---|---|
apical organ (ao) | + | + | + | completely lost |
median neurite bundle of the preoral lobe (mn) | + | + | + | completely lost |
anterior marginal neurite bundle of the preoral lobe (am) | + | ― | + | completely lost |
ventrolateral branches (vlb) | + | ― | + | completely lost |
posterior marginal neurite bundle of the preoral lobe (pm) | + | + | + | completely lost |
sensory field (sf) | + | ― | ― | completely lost |
neurites and perikarya innervating the oral field (ofn) Can be observed by TEM only | ― | ― | ― | completely lost |
tentacular nerve ring (=main nerve ring) (tn) | + | + | + | completely maintained (5HT, FMRFamide, alfa-tubulin) |
minor nerve ring (mn) | ― | ― | + | completely maintained (alfa-tubulin) |
mediofrontal tentacular neurite bundle (mf) | ― | + | + | undergoes changes: can not be detected via LSCM and changes in number of neurites (from 100 to 10) (alfa-tubulin) |
laterofrontal tentacular neurite bundles (lf) | ― | ― | + | completely lost; definitive neurite bundles form de novo (alfa-tubulin) |
medioabfrontal tentacular neurite bundle | ― | ― | ― | appears in juveniles (alfa-tubulin) |
lateroabfrontal neurite bundles (la) | + | ― | + | completely maintained (5HT, alfa-tubulin) |
two dorsolateral groups of perikarya (gp) | + | ― | ― | completely maintained and give rise to the definitive dorsal ganglion (5HT) |
telotroch nerve ring (ttn) | + | ― | ― | completely lost |
neurites and nerve cells innervating the epidermis of the larval trunk (sg(=mdn?)) (neurite bundles of the second group [8]) | + | ― | ― | probably maintained and give rise to the most dorsal neurites (5HT) |
neurites of the esophagus (es) | + | + | + | completely maintained (5HT, FMRFamide, alfa-tubulin) |
neurites and perikarya innervating the midgut (pmg) | ― | + | ― | completely maintained (FMRFamide, alfa-tubulin) |
anal nerve ring (ar) | ― | + | ― | probably undergoes changes, because in juveniles exhibits 5HT-like immunoreactivity |
neurites and perikarya innervating the metasomal sac (nms) | + | + | ― | completely maintained (5HT, FMRFamide, alfa-tubulin) |