Sections were de-waxed using Histo-clear (Lamb, Inc.) for 5 min. and then re-hydrated in a graded series of ethanol (100%, 95%, 70%; 2 min. per incubation). The slides were then washed in deionised water and 16 PBS (two 5 min. incubations). The endogenous peroxidase activity was blocked by a 5 min. incubation in 3% hydrogen peroxide. After two 5 min. washes in PBS the slides were blocked in 1% BSA in 16 PBS-Tween for 20 min. After addition of the primary antibody (rabbit-anti acasein antiserum; 1:100 dilution in 16PBS-Tween) the slides were incubated at 4uC overnight. The slides were then washed twice for 5 min. in 16 PBS and the secondary antibody was added (horseradish-peroxidase linked goat anti-rabbit serum; 1:1000 dilution in 16 PBS-Tween). After a 30 min. incubation at room temperature the slides were washed twice for 5 min. in 16PBS-Tween.