Variation of steroid concentrations during the reproductive cycle of the clam Ruditapes decussatus: a one year study in the gulf of XXXX  s area.

@entity251 @entity1420 @entity12191 @entity53 @entity230
@entity1420 , @entity251 and @entity53 -17beta were measured by radio-immunoassay (RIA) in the gonads of the clam Ruditapes decussatus. The reproductive cycle was also investigated. Our study covered a period of one year, from September 2003 to August 2004. The chosen site "Kerkennah", located out of industrial effluents, belongs to the gulf of @entity12191  s area (Tunisia). @entity230 varied from 178 to 2459 pg g(-1) wet mass for @entity1420 , from 40 to 326 pg g(-1) wet mass for @entity251 and from 10 to 235 pg g(-1) wet mass for @entity53 -17beta in females. However in males, these @entity230 ranged from 304 to 2303 pg g(-1) wet mass for @entity1420 , from 81 to 381 pg g(-1) wet mass for @entity251 and from 48 to 168 pg g(-1) wet mass for @entity53 -17beta. The reproductive cycle of R. decussatus, investigated by histological examination of gonadic sections, showed that gametogenesis occurred from April to February in males and from April to November in females. @entity1420 and @entity251 increased at the end of gametogenesis in both sexes. The highest @entity53 -17beta was recorded at the beginning of vitellogenesis in females. Fluctuations in the levels of sex @entity230 during the reproductive cycle suggest their possible role as endogenous modulators of gametogenesis in R. decussatus. Although this species is considered as gonochoristic, 0.83% of hermaphrodites were observed.
