Figure 1: Dose-dependent curves of sex steroid hormones on in vitro molting of muscle larve of T. spiralis. One hundred muscle larve (ML) of T. spiralis were incubated for 36 hours with different concentrations of progesterone (P4), estradiol (E2), or testosterone (T4). Progesterone inhibited the molting rate of the muscle larva of T. spiralis in a concentration-independent pattern (a). Estradiol inhibit only at 50 nM concentration (b), while testosterone has no any effect on molting (c). Each point represents the mean (SD) of quintuplicate determinations of the number of larvae in molting process.