Bleaching of Melanomacrophages from Tissues of Ectothermic Vertebrates for Later Use of Immunohistochemical and in Situ Hybridization Technique

Abstract— Due to the large quantity of melanomacrophages in the organs of the ectothermic vertebrates, with special interest in the ranids and fish, with their brownish melanin granules, we decided to test the MELANIN removal technique, in order to facilitate the observation of the organ fragments in the slides, under the direct light optical microscope, when using the antibodies and biotinylated probes.

Thus, the melanin bleaching study favored the visualization of the diaminobenzidine chromogen (DAB) without interfering with the antigen-antibody affinity of immunohistochemistry and without interfering with the technique by which specific nucleotide sequences are identified in histological sections. (of DNA or RNA, endogenous, bacterial or viral).

This bleaching of melanin from tissues avoided false positive results, without interfering with the IHQ and ISH techniques for Mycobacterium spp and Francisella spp in fish.