Cell Identification: Body Neurons
Hermaphrodite Ventral Cord Motor Neurons I
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Identification of ventral cord motor neurons are best done during L1 stage when the cell bodies occupy invariant positions. Note, however, at this stage postembryonic motor neurons with dorsal commissures (i.e. AS, VD) will not be seen.
Commissures on the right side:
AS1, AS2, AS3, AS4, AS5, AS6, AS7, AS8, AS9, AS10, AS11
DB1, DB3, DB6, DB7
DD2, DD3, DD4, DD5, DD6
VD1, VD3, VD4, VD5, VD6, VD7, VD8, VD9, VD10, VD11, VD12, VD13
Commissures on the left side:
DA1, DA3, DA4, DA5, DA6, DA7
DB2, DB4, DB5
Schematic Diagrams of Ventral Cord Motor Neurons
In all diagrams, axon processes with neuromuscular synapses (NMJ) are shown as whereas dendritic processes where synaptic inputs are received are shown as .
Class A axons run forward in both cords (VNC and DC) whereas the class B axons run backwards. The dendritic branches of the dorsal and ventral class A neurons run in opposite directions as do those from class B neurons. Ventral class D neurons receive their synaptic input on the dorsal side and give NMJ's on the ventral side. The dorsal type D neurons have half the periodicity of their ventral counterparts and receive synapses on the ventral side and give NMJ's on the dorsal side. Class AS neurons only synapse on the dorsal side and have no ventral counterpart, whereas, the class C neurons only synapse on the ventral side. The synapses from class C motor neurons onto body muscles are less dense than for the other classes (White et al., 1976).
|DA and DB Neurons
|DD and VD Neurons