Fig. 3. Effects of laparotomy on rearing. Vertical counts were determined after sham surgery ( open bars ) or laparotomy ( dark bars ) (mean ± SEM) either in the same groups of animals each day after surgery ( A ) or in separate groups of animals that were exposed to the chamber only once on the indicated postoperative day ( B ). * Significantly different from sham, P ≤ 0.05.