PVQ is a pair of interneurons with cell bodies in the lumbar ganglia. Processes enter the
posterior extremity of the ventral cord via the lumbar commissures; initially, both run
anteriorly on the right-hand side of the hypodermal ridge. When the end of the pre-anal
ganglion is reached, PVQL crosses over to the left-hand side of the hypodermal ridge and runs
all the way along the ventral cord up to the nerve ring in this position, whereas PVQR runs
on the right-hand side along with most of the processes of the ventral cord (figure 15). As the
ring is approached, the processes move up to the dorsal surface of the neuropile of the ventral
ganglion. The processes then run round each side of the ring, near the posterior face, in close
association with the processes of ASJ. They meet and terminate on the dorsal mid-line; there
is a gap junction at the point of contact on the JSH series but the two processes do not quite
touch on the N2U series. The processes of PVQ have prominent lateral (b, c) and dorsal (d)
vesicle-filled varicosities. There are many dark vesicles present in these
regions; the rest of the cytoplasm stains rather lightly, giving the processes of PVQ a characteristic appearance (BDU looks similar but has smaller processes with fewer vesicles). The main synaptic output is to AIA (a, b, c, d), sometimes in dyadic combination with ASK (b, c). There are also a few minor
synapses to AVF and HSN. The synaptic input is almost exclusively from ASJ (*a), in the nerve
ring. There are gap junctions to ASK (*a, b) and ADA. There are practically no synapses of
any consequence in the ventral cord, except possibly for a few synapses from PHA (*b) in the
tail.
Magnifications: (a) x 25500, (b-d) x 17000.
PVQ ventral card synapses
partners |
gap junctions |
synapses from |
synapses to and corecipients |
HSN |
- |
- |
1 |
AVL |
- |
- |
1 |
DD1 |
- |
- |
VD1 |
VD1 |
- |
- |
DD1 |
DVB |
- |
- |
DVC |
DVC |
- |
- |
DVB |
PVQ |
2 |
- |
- |
PHA |
- |
4m |
- |
VC3 |
- |
2+1m |
- |
AVH |
- |
1+2m |
- |
AVK |
- |
1 |
- |
AVJ |
- |
1 |
- |
AVF |
- |
1m |
- |
AVG |
- |
1m |
- |
ADA |
- |
- |
- |