Human corpus luteum: immunocytochemical localization of epidermal growth factor

Six corpora lutea (day 17 to day 25) of the menstrual cycle and four ovarian stromal tissues from seven cycling women were examined for the presence of epidermal growth factor (EGF) by immunocytochemistry with the use of the indirect peroxidase-antiperoxidase (PAP) procedure. After tissue sections of 4 micron were mounted, endogenous peroxidases were removed with hydrogen peroxide, and the sections were incubated for 1 hour at room temperature followed by 16 hours at 4 degrees C with a highly specific antisera for mouse EGF (mEGF), nonimmunized normal rabbit serum, or antiserum preadsorbed with excess antigen. After the reaction with the second antibody (goat antirabbit IgG) for 1 hour at room temperature, the peptide was localized by use of PAP and 3.3'-diaminobenzidine as the chromogen. EGF could be localized in the luteal cells of five corpora lutea (day 17 to day 25) but not in a corpus luteum of day 22 and all ovarian stromal tissue examined. The localization of immunoreactive EGF in the human corpus luteum demonstrates directly for the first time the presence of this growth-promoting peptide in this tissue, which suggests its local production.