Worm Breeder's Gazette 3(1): 18b
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.
There are only three out of the adult complement of five classes of motor neurone present in the ventral cords of L1 juveniles. The total of 15 cells is made up of 5 DB's, 6 DA's and 4 DD's. The sequence of cell types is invariant in juvenile cords thus enabling cells to be identified in live animals by their relative positions in the cord. All cells of a particular class were killed by means of a laser microbeam and any subsequent alterations in behavior observed. It was found that larvae with ablated DA's could not back up but moved forward normally, whereas those without DB's had difficulty moving forward but showed normal backing behavior. The latter effect is somewhat masked by head movements which were always normal. Animals without DD's were severely uncoordinated when moving in either direction. These observations are in accord with the predictions of Dick Russel's model of the functioning of the ventral cord.