In C. elegans, Fem-1, encoding an ankyrin repeat protein, is a component of the signal transduction pathway controlling sex determination . There were three members in the Fem-1 gene family (designated as Fem-1a, Fem-1b, and Fem-1c) in our transcriptome database, which were homologs of the nematode Fem-1 protein . It is reported that Fem-1 might function in early sex determination and late gonad development in the crab . However, in the present study, the four homologs of Fem-1 are not significantly upregulated in the secretory phase of AG.