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Figure 4: Sequence of perinatal manipulations prior to tests of respiration and nipple attachment. The top portion of the figure depicts injections of citral or saline into individual amniotic sacs, which was followed by compressions or no compressions (control). Pups were then delivered by caesarian section. Over the next two hours, individual pups were treated with thermal and odor regimes designed to mimic early postnatal events, shown in the lower sections of the figure. For some pups, citral was present prenatally and postnatally. Saline was used on the gauze pads of the control pups (see text). The grey and white areas around each pup depict the olfactory treatment (citral or saline control) of the moistened pads.