Progesterone-like substance in ovary and hepatopancreas of Uca vocans borealis

We study the temporal variation in amount of progesterone-like substance in tissuesof the fiddler crab, Uca vocans borealis. Both HPLC and radioimmuno assay (RIA) were employed to determine the amount of a progesterone-like su bstance in extracts of ovary and hepatopancreas. The results show that, dur ing the breeding period (egg-carrying, January-September), the progesterone -like substance concentrations in ovaries and in hepatopancreases of the cr abs studied were 13.8-29.3and 7.7-17.2 ng per gram of tissue, respectively; while the values dropped to 1.0-2.1 and 4.8-6.8 ng per gram of tissue, res pectively, during the nonbreeding period (non-egg-carrying, October-Decembe r).