FURTHER STUDIES ON THE USE OF TETRAZOLIUM IN THE BIOLOGICAL ASSAY OF OESTROGENS

Abstract

SUMMARY: An extensive description is given of the techniques and schedules used in the tetrazolium assay for oestrogens. Among the variables studied, volume of tetrazolium solution, dissection speed and the use of albumen solution were without effect. Priming of mice increased overall formazan production and reduced variability, but did not increase sensitivity or slope of the dose response line for oestrone. Other possible variables affecting the assay are discussed. Three randomly bred strains of mice were comparable in sensitivity and precision, while a single inbred strain (CBA) was so variable as to be unsatisfactory for routine use. Oestradiol-3:17β was 3·7 times as active as oestrone, and oestriol approximately half as active. The slope of the dose-response line for oestriol was significantly lower than those for oestrone and oestradiol. Diethylstilboestrol was slightly less active than oestradiol-3:17β and equal in slope.