The nuclear localisation of Annexin A7 in mice observed in immature cells at E16 and differentiated adult neurons could be only detected as a strong signal when the brain sections were pre-treated with trypsin before antibody staining. This procedure is thought to allow the antibodies to access epitopes masked by the formaldehyde fixation. Methanol fixation of cultured cells led to inconsistent results. Antigen retrieval in formalin-fixed and paraffin-embedded tissue sections employs various heating or proteolytic pre-treatment methods [[15-17]; Ein Handbuch für die Histologie, dianova GmbH, Hamburg, Germany]. These methods can result in moderate or strong specific antibody staining, but the detectability of other antigens might be decreased. Moreover, the optimal pre-treatment has to be individualised for each antigen.