Figure 2.

Mean ± S.E.M frequencies of pup licking across the three, 10-min sessions rated on postnatal (PN) days 4, 7, and 10 are shown for male pups (squares) and female pups (circles). Data from pups raised in mixed-sex litters are depicted by closed symbols and data from pups raised in single-sex litters are depicted by open symbols. Male pups from mixed-sex litters are licked the most whereas male pups from single-sex litters are licked the least, particularly on PN4 and PN7. # LGC; % LGC × Sex; P’s<0.01.