Changes in steroid concentrations in follicular fluid and sexual behavior during pseudopregnancy in the rabbit

Changes in sexual behavior and progesterone, oestrone, oestradiol, testosterone and androstenedione concentrations have been studied in the follicular fluid of 25 pseudopregnant rabbits on Days 6, 9, 12, 15 and 18. The sexual behavior score seemed to rise at the end of pseudopregnancy and follicular steroid levels were higher on Days 6 and 18 of pseudopregnancy than on Days 9, 12 or 15. The generalized distance D2 of Mahalanobis showed the existence of four periods during pseudopregnancy: Day 6, Days 9 and 12 which were similar, Day 15 and Day 18. These stages were found to differ by a compound of the sexual behavior score and the concentrations of androgens and oestradiol in follicular fluid. There was no relationship between sexual behavior and follicular steroid concentrations. Nevertheless, undetectable levels of oestradiol in the follicular fluid were only observed in deeply dioestrus females.