Effect of prenatal LPS on play behavior. Means + SEMs of the number of play events displayed in a ten-minute testing period. (I): in treatment-matched pairs, there was a significant interaction of treatment X sex for Total Play (ANOVA, p < 0.005), Boxing & Wrestling (ANOVA, p < 0.002) and Pinning (ANOVA, p < 0.04), with LPS reducing play in males but not in females. *: Planned comparisons confirmed that LPS Males showed less Total Play (Fisher’s PLSD, p < 0.006) and Boxing & Wrestling (Fisher’s PLSD, p < 0.0008) than did Saline Males. #: Saline Males had higher scores than did Saline Females for Total Play (Fisher’s PLSD, p < 0.05) and Boxing & Wrestling (Fisher’s PLSD, p < 0.03). In treatment-mixed pairs, no significant interactions of treatment X sex were found. Planned comparison, however, suggested that LPS reduced Pouncing in males (Fisher’s PLSD, p < 0.04) but not in females. By definition, when one animal in a pair shows Boxing & Wrestling, so does the other. For that reason, we show only one differently shaded bar for LPS and Saline animals for Boxing & Wrestling rather than two identically sized bars for males and females in mixed-treatment pairs.