The cheracteristic features of immature rats were the high serum amylase and LAP activities. The activities of the amylase in the uterine wash of immature rats were absent. Amylase activity was absent from uterine wash during late estrus and very high during metestrus. Serum amylase was high during late proestrus and early estrus. Lipase activity was very hgih in uterine wash during late estrus then dropped suddenly during metestrus. Serum lipase showed a gradual increase from proestrus reaching its peak during early estrus.
LAP activity in uterine wash was very low during proestrus and became high during early and late estrus. Serum LAP activity was high during proestrus then declined gradually during the following stages.