Figure 5: Changes in the carbohydrate chain structure of transferrin during the ovulation phase. (A) Glycans of transferrin in the control. (B) Glycans of transferrin in the ovulation phase. Although sialic acid residues were not detected in major ion peaks observed at m/z 1892 and 2054, sialic acid residues were detected in ion peaks observed at m/z 2712 and 2858.