Contribution of porcine follicular fluid in the process of fertilization in vivo

Two experiments were conducted to determine if follicular fluid (FF) enters the oviduct and plays any role in the postovulatory distribution of sperm cells within the oviduct. Oestrus and ovulation were synchronized by feedin g of Regumate(R) and application of 1,000 IU PMSG and 500 IU hCG. Experimen t I: The steroid contents of FF in relation to the oviductual fluid prior t o ovulation and within the oviductual fluid before and after ovulation were analyzed in group 1 (n=7). For this purpose aspiration of FF from follicle s and salpingectomy of the left ovary was laparoscopically performed prior to ovulation (34-36 h after hCG). The oviduct of the right control side was removed after ovulation (42-44 h after hCG). To prevent the entry of FF in to the oviduct, follicles of the left ovary were aspirated (group 2, n=7) o r the left oviduct was ligated between ampulla and infundibulum (group 3, n =7) prior to ovulation. Bilateral salpingectomy were done after ovulation, respectively. Oviducts were flushed with 1 mi saline and the samples were a ssayed for steroids by RTA methods. In group 1 the progesterone concentrati on within the oviductual flushing did not differ before and after ovulation (0.09+/-0.13 vs. 0.12+/-0.16ng ml(-1)). Withdrawal of FF from the left ova ry by aspiration (group 2) or ligation of the oviduct (group 3) did not inf luence the steroid content within the oviducts. Similar low concentrations were measured in left and right oviducts after ovulation (0.29+/-0.17 and 0 .22+/-0.19 vs. 0.24+/-0.35 and 0.21+/-0.22 ng ml(-1)). The high content of follicular fluid progesterone (269.7+/-67.9 and 389.6+/-226.5 ng ml(-1) in group 1 and 2, respectively) was not reflected in oviductual fluid. Compare d to FF, only 0.03 to 0.07 % of progesterone concentration were found withi n the oviductual flushings. Experiment II: Gilts were inseminated time-orie nted with fresh semen (4x10(9) sperm cells/100 mi) 36 h after hCG injection . To prevent the entry of FF into the oviduct unilaterally the left oviduct was ligated between the ampulla and infundibulum (group 1, n=18), FF of fo llicles of the left ovary was aspirated (group 2, n=8) or the infundibulum was taken from the ovary and fixed in an adovarian position at the uterine wall and sutured with endoscopical knots (group 3, n=8). The right oviduct served as control. All endoscopic handling was done 30 minutes after insemi nation. Bilateral salpingectomy was performed postovulatory (56.5 h after h CG, i.e. 20.5 h post insemination, respectively) by laparotomy. The ampulla ry and isthmic sections of the oviducts were flushed separately with 0.25 m i PBS. Ligation of the oviduct (n=10 gilts) seems to influence sperm cell d istribution within the oviductal sections (0 and 12.4x10(3) sperm cells in the ligated ampullary and isthmic sections vs. 14.6 and 42.9x10(3) in the c ontrol). But it remained open whether the different sperm cell distribution is related to the failure of FF or to the surgical ligation procedure. The refore, additionally in 24 gilts a ligation, shame-ligation or the FF withd rawal by aspiration was carried out. Manipulation of the left oviduct resul ted in a reduced number of sperm cells compared to the contralateral contro l oviduct (ligation -5.47, aspiration -10.67, shame-ligation - 9.89x10(3) s perm cells vs. 16.14, 14.05 and 18.21x10(3) sperm cells in the right contro l oviducts, respectively). However due to the high variation in sperm cell number these differences are not significant. Altogether we conclude that 1) only an unimportant amount of FF reaches the oviduct at ovulation and 2) FF is not a trigger of sperm cell distribution within the porcine oviduct at ovulation.