Study of the metabolism of steroids in larvae of the fleshfly Sarcophaga bullata.

1. Larvae of the fleshfly Sarcophaga bullata were injected with several 3H C21 and C19 steroids. After different incubation times, the larvae were homogenized and the metabolites were extracted and fractionated by Sephadex LH 20-, paper- and thin-layer chromatography. The chromatographic mobility of the labeled zones was compared with that of standard steroids. 2. Progesterone and 17 alpha-hydroxypregnenolone were metabolized to 17 alpha-hydroxyprogesterone. Androstenedione, 17 alpha-hydroxyprogesterone and dehydroepiandrosterone were converted to testosterone. Transformation of pregnenolone to progesterone or 17 alpha-hydroxypregnenolone was not observed. 3. C21 or C19 steroid formation from cholesterol could not be demonstrated. 4. Sixteen metabolites, different from all our standard substances have been found. Their structure remains to be elucidated.