In mammals, coagulation factor V participates in the coagulation process. In zebrafish, a coagulation factor V (cf5) cDNA was previously characterized [63] . According to these authors, several lines of evidences including biochemical and phylogenetic analyses suggest that the modern coagulation pathways found in mammals could also be functional in fish. Furthermore, it was previously shown that cultured rabbit macrophages were able to generate factor V procoagulant activity [64] . In the present study, we observed a dramatic increase of cf5 gene expression in the ovary during oocyte maturation. However, no significant difference was observed between late and postvitellogenesis. From these observations we could speculate that, immediately prior to ovulation, the trout ovary secretes coagulation factors in order to prevent bleeding from ruptured ovarian follicles at the time of ovulation. Interestingly, the transcriptomic analysis showed that a transcript exhibiting sequence similarity with clotting factor C (Clone # 251, Table 3 ) was also over expressed immediately prior to ovulation.