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PVN is a set of two interneurons/motoneurons with cell bodies situated in the lumbar
ganglia. Anteriorly directed processes enter the pre-anal ganglion via the lumbar commissures
and then run alongside each other near the centre of the ventral cord. Prominent lateral
branches enter the anterior regions of the vulva (e), running underneath the vm1 vulval
muscles. These branches become quite large and contain a few vesicles, although no obvious
focal synaptic contacts have been seen. The processes of PVN also branch extensively in the
anterior extremities of the ventral cord; PVN is the most highly branched class of neuron in
the nervous system. Many of the branches probably develop quite late, as PVN neurons in the
JSH series (an L4 larva) had few branches. The branches of PVN tend to stay in the same
neighbourhood as the main processes, running alongside them (they have been drawn
separated for clarity). The main processes of both PVNL and PVNR enter the nerve ring on
the right-hand side and run round it near the inside surface of the neuropile, in close association
with the processes of BDU. PVNL has an additional branch, which enters the ring on the left-
hand side, travelling in the same neighbourhood as the other branches of PVN. The synapses
that are made by PVN are all rather small, with few vesicles in their synaptic terminals. In the
nerve ring there are a few synapses to and from BDU (a, *c) and to AVJ (b). In the ventral
cord the synapses are more numerous and are mainly onto AVD, NMJs (d), VDn, DDn (d), AVJ and PVW. There is a single gap junction to both HSN and PVQ, and a couple
to AVB.
Magnifications: (a, b) x 25500, (c, d) x 17000, (e) x 12750.
PVN ventral cord synapses
partners |
gap junctions |
synapses from |
synapses to and corecipients |
AVD |
- |
- |
2AVD, PQR, AVJ, AVA, AVE |
PQR |
- |
- |
AVD, AVB, PVW |
NMJ |
- |
- |
3, VD12, 2DD1, VD3 |
PVW |
- |
- |
PQR, PVN, HDC |
AVB |
2 |
1m |
1, PQR, HDC |
PVN |
- |
4m |
AVL, PVW, AVG, VD4 |
PVT |
- |
- |
1,AVL |
AVA |
- |
- |
2, PVC, AVD, VD4, VA6 |
AVL |
- |
- |
2PVN, PVT, VA6 |
HDC |
- |
- |
PVW, AVB |
AVJ |
- |
- |
2, AVD, AVJ, HSN, BDU |
PVC |
- |
- |
1,AVA |
VD12 |
- |
- |
NMJ |
AVG |
- |
1+1m |
PVN |
BDU |
- |
- |
AVJ |
AVE |
- |
- |
2,AVD |
AVF |
- |
1m |
RIF |
RIF |
- |
- |
AVF |
AVH |
- |
1m |
- |
PVQ |
1 |
- |
- |
DD1 |
- |
- |
2NMJ |
VD3 |
- |
- |
NMJ, DD2 |
DD2 |
- |
- |
VD3 |
VD4 |
- |
- |
2, AVA, PVN |
VC2 |
- |
- |
1,VC3 |
VC3 |
- |
1m |
VC2 |
VA6 |
- |
- |
AVL, AVA |
DVB |
- |
- |
VD7 |
VD7 |
- |
- |
DVB |
HSN |
- |
- |
AVJ |
DB3 |
- |
- |
1 |
DD3 |
- |
- |
1 |
LUA |
- |
1m |
- |
VA11 |
- |
2m |
- |
VD12 |
- |
- |
NMJ |
PDA |
- |
1m |
- |
|
|
