Worm Breeder's Gazette 2(2): 32
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.
The arrangement of internal hypodermal ridges with their associated basement membranes seems to confine nervous tissue to specific regions and may define the basic shape of such structures as the nerve ring. The body musculature is arranged in four quadrants each consisting of about 24 cells. The first 4 cells in each quadrant receive their synaptic input solely from the nerve ring; the next four jointly from the nerve ring and ventral cord and the remainder solely from the ventral cord. Muscle cells which receive their synaptic input from the nerve ring send out arms which at first run outside the nerve ring and then turn and enter the inside of the ring from the rear so as to lie next to the motor neurones which line the inner surface of the ring. The muscle arms here sort themselves out into 8 groups, each quadrant being sub-divided into two rows. There are nine classes of motor neurones in the nerve ring and each individual neurone synapses onto two adjacent muscle rows defining either a quadrant with a 90 edge or one with a 45 edge. Neurones in six of the classes cover 90 quadrants; two of the classes have neurones that cover 45 quadrants and one class (the inner labial mechano-receptor which has 6 fold symmetry) has neurones which cover both. The motor neurones can either themselves be sensory neurones or receive their synapses directly from separate sensory neurones or via interneurones. Some interneurons seem to be specific to a particular type of receptor while others have a more generalized integrative role.