Sex differences in the pattern of esterase-active antigens in microsomes from various rat strains

Esterase-active antigens present in male and female liver microsomes isolated from three different rat strains (Sprague-Dawley, Wistar and Dark Agouti) were characterized in crossed immunoelectrophoresis in combination with a zymogram method for esterase activity. No qualitative but some quantitative differencies were encountered between the sexes. Thus, two out of ten antigens were present in significantly lower and one in significantly higher concentrations in male than in female microsomes, demonstrating that although the overall esterase activity in liver may be similar for males and females, the concentration of the individual antigens does vary between the sexes. No qualitative or quantitative differences in the pattern of esterase-active antigens were found between the different strains.