Worm Breeder's Gazette 1(1): 17a
These abstracts should not be cited in bibliographies. Material contained herein should be treated as personal communication and should be cited as such only with the consent of the author.
We have been studying the structure of the N2 hermaphrodite ventral and dorsal nerve cords for some time and have recently extended these studies to L1 larvae prior to the post-embryonic development that takes place. The adult has 5 classes of motor neurone in the ventral cord designated A, B, C, AS and D. Classes A, B and D can be divided into two sub-classes; those that innervate the ventral muscles and those that have axones that run in the dorsal cord and innervate the dorsal muscles. Class AS only innervate dorsal muscles and class C only innervate the ventral muscles (predominantly the sex specific muscles). Classes A, B, and AS are driven from interneurones that come from the nerve ring. Class D neurones that innervate the ventral side have a dendritic process on the dorsal which is driven by all the other motor neurones active in its locality. Conversely, dorsal type D receive their innervation from ventral motor neurones and innervate the dorsal body muscles. If all the motor neurones which are known to develop post-embryonically are subtracted one is left with the complement of motor neurones which is present in the L1 larva and these turn out to be dorsal A, B, and D. This seemed paradoxical, but when the nerve cords of an L1 were looked at it was seen that the cells which were dorsal type D's in the adult innervate the ventral side of the L1, receiving their innervation from a dendrite on the dorsal side which is driven by the dorsal type A and B motor neurones. Thus it seems as if these cells 're-wire' in the course of development. We are now trying to find out whether this re-wiring is induced by the arrival of the new motor neurones or is autonomous.