Fig. 4. M4 and M2 stimulated isthmus/terminal bulb behaviors in the Diplogasteridae, Cephalobidae, and Panagrolaimidae families. Laser ablations in select species from the Diplogasteridae, Cephalobidae, and Panagrolaimidae families. (A) Pristionchus pacificus PS312 (Diplogasteridae): M4 ablation caused a reduction in isthmus/TB peristalsis and also a decrease in corpus pumping. (B) Cephalobus sp. DWF1301 (Cephalobidae): M4 ablation caused a reduction in isthmus peristalsis/TB pumping. (C) Panagrolaimus sp. PS1159 (Panagrolaimidae): M4 ablation caused a reduction in posterior isthmus/TB pumping. M2 ablation caused a reduction in anterior isthmus peristalsis and also a reduction of corpus pumping. The effects on corpus pumping of M4 ablation in P. pacificus and M2 ablation in Panagrolaimus sp. PS1159 are probably secondary to the defects in peristalsis (see Results). Asterisks indicate statistically significant differences from controls by two-tailed t-test (**P<0.01, *P<0.05).