Cell proliferation markers in the transplanted canine transmissible venereal tumor [Marcadores de proliferação celular no tumor venéreo transmissível canino transplantado]

Adult male mongrel dogs were subcutaneously transplanted with the canine transmissible venereal tumor (TVT) on the hypogastric region. Twelve specimens of tumors were collected, half during the proliferative phase and the other half during the regressive phase. Fragments of the tumor were fixed in 10% buffered formalin and routinely processed for light microscopy. Sections of 4μm were stained by Schorr or AgNOR or either immunostained for MIB1 (Ki67). Schorr stain, AgNOR and MIB1 showed an increased proliferative activity through mitotic index, nuclear argyrophilic protein stain and cycling tumoral cells in the growing tumors, respectively. All of the three cell proliferation markers were able to distinguish the TVT in both evolution phases. MIB1 monoclonal antibody was the best in the morphologic evaluation of growth and regression of TVT. This resulted in higher values than AgNORs counting and mitotic index. MIB1 immunostaining was the most effective parameter of the proliferative activity of TVT. However, a significant correlation has been detected only between mitosis counting and AgNORs.