In the hippocampal formation we detected prominent Annexin A7 immunostaining in the stratum pyramidalis and in the dentate gyrus and also a weak astrocytic staining (Fig. 4C). The astrocytes are mainly localized in the area between cells exhibiting nuclear Annexin A7 staining and show the protein also in the nucleus and the cytoplasm (data not shown). When we analyzed the pyramidal neurons in the hippocampus at a higher magnification we found that Annexin A7 again mainly localized to the nuclei (Fig. 4G). Polyclonal antibodies gave a similar staining pattern (data not shown). The intense nuclear staining was absent in controls either stained only with the secondary antibody (Fig. 4D) or in brain sections derived from AnxA7-/- mice stained for Annexin A7 (Fig. 4H). The residual staining seen in the AnxA7-/- brain is unspecific as it is also present in corresponding negative controls lacking the primary antibody. The absence of Annexin A7 protein in brain and other tissues of the AnxA7-/- mouse has been verified in [10]. In another actual study of the knock out mouse we detected a thickened basal membrane and a widened intercellular space. This may cause unspecific binding of the secondary antibody.