Human ovarian follicular fluid has functional systems for the generation and modulation of thrombin.

OBJECTIVE: To determine whether prothrombin is present in follicular fluid and whether the enzymatic pathways for prothrombin activation are similar to those in plasma.
DESIGN: Follicular fluid samples collected at the time of oocyte harvest for an assisted reproductive technology procedure (ART) were analyzed for a panel of hemostatic proteins with use of a combination of functional, chromogenic, and Western ligand blot analysis.
SETTING: An ART clinic and an academic research laboratory. PATIENT(S): Women undergoing ART. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Determination of components of thrombin generation and thrombin modulatory systems using functional and antigenic assay procedures. RESULT(S): Both prothrombin and components of the prothrombinase enzyme complex, which includes factors V, VII, and X, are present in follicular fluid. Other hemostatic proteins, including factors VIII and IX and vonWillebrand factor, are absent. The direct activation of prothrombin to thrombin is similar in follicular fluid and plasma. Like plasma, inhibitors of both thrombin and thrombin generation, including antithrombin, protein C, and alpha2-macroglobulin, are present in follicular fluid. CONCLUSION(S): Only a select group of hemostatic plasma proteins are present in follicular fluid. There is no direct correlation between molecular size and concentration of individual proteins in follicular fluid. These results indicate that the proteins involved in the thrombin-generating and thrombin modulatory pathways may be derived from ovarian cells, suggesting that thrombin may have a role in folliculogenesis.