Pregnancy-induced autogrooming in mice: the effects of nipple removal.

As pregnancy advances, Rockland-Swiss albino mice spend increasingly more time engaged in autogrooming. By gestation day 18 (the day prior to parturition), the total duration of autogrooming (a composite measure) as well as the duration of nipple line grooming is significantly longer than that displayed by virgin and early pregnant females. Nipple excision (i.e., thelectomy) performed prior to pregnancy reduces the time GD 18 dams spend licking nipple line regions without producing a concomitant decrease in the duration of grooming all regions. It is unlikely, therefore, that peripheral stimulation of the nipple line regions via self-licking contributes to the heightened display of grooming by pregnant mice.