MusFIG 15A: Arrangement of body wall muscle cells in the adult hermaphrodite.

The animal is filleted along the dorsal midline. Lineal origins of the muscle cells are indicated. Each quadrant contains 24 mononucleate diploid cells, except for the ventral left quadrant, which contains 23 cells. Red lines separate the head, neck and body muscle, which receive distinct innervations from motor neurons. The 16 head muscle cells (A and B blocks) in eight rows receive innervation exclusively from the nerve ring motor neurons and motor neurons of the ventral cord, whereas body muscles receive innervation only from ventral nerve cord motor neurons. (Solid green cells) Post-embryonic additions to the muscle quadrants. (dm) Dorsal midline; (vm) ventral midline. (Based on Sulston and Horvitz, 1977; Sulston et al., 1983; Moerman and Fire, 1997.)

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