Analysis of uterine flushings using a double determinant ELISA. Anti-VNTR McAb BC2 was used as capture antibody with either anti-VNTR McAb BC3 (white bars) or anti-MUC1/SEC McAb 7H10/5 (grey bars) as detector antibodies. Use of 7H10/5 results in the identification VNTR-containing MUC1/SEC species, thus confirming expression of the alternatively spliced secretory isoform in endometrium. The vertical axis represents absorbance at 405 nm. Individual controls in which capture, uterine flushings and detector antibodies were omitted from the assay were performed for each antibody. For BC3 the mean control absorbance values obtained was 0.172 (sd = 0.0408) and for 7H10/5 was 0.316 (sd = 0.145).