Figure 4

Annexin A7 is present in neurons and astrocytes of the cortex temporalis and hippocampal formation of 10-weeks-old mice. (A) Low magnification of the cortex temporalis presents an Annexin A7 expression in cells of the pial border, in neurons of all six isocortical laminae, and a weak signal in the adjacent white matter. (B) Corresponding section stained with GFAP. (C) Staining in the Stratum pyramidalis (a) and in the dentate gyrus of the hippocampus; square, a higher magnification of acorresponding area is given in (G,H). An intense Annexin A7 immunostaining is detectable. (D) Corresponding section stained with secondary antibody only. (E) Presence of Annexin A7 in pyramidal neurons (lamina pyramidalis externa) of the isocortex temporalis. These neurons were identified based on their morphology, distribution and lack of GFAP staining. AnnexinA7 exhibits a punctate staining, which is pronounced in the nucleus (arrowhead). (F) Higher magnification of image (A) also shows Annexin A7 in nuclei of neurons (lamina granularis externa (corpuscularis), arrowhead) and in the cytoplasm and nuclei of astrocytes (lamina molecularis, arrow; GFAP-confirmed). (G) Higher magnification of the pyramidal neurons in the hippocampus confirms the presence of the Annexin A7 protein in the nucleus (arrowhead) of mature neurons. (H) To further confirm this, a similar section derived from an AnxA7^-/- mouse was stained with the annexin specific antibody and lacked the nuclear signal. The residual stain of the tissue is unspecific, as it is also observed in controls of the AnxA7^-/- brain omitting the primary antibody (data not shown). All paraffin sections were stained with mAb 203–217 (A, C, E, F, G) or anti-GFAP-antibody (B). The hippocampal control section (D) lacks the primary antibody.