Reproduction in Domestic Animals

Fertilization in the Porcine Fallopian Tube 249to the time of the oestrous cycle, being higher in theisthmus than in the ampulla, probably owing to thelarger secretory capacity of the latter (Tienthai et al.2001). The S-GAG-levels increase significantly in isthmusduring the pre-ovulatory oestrus, to decreasetowards metoestrus, occurring in both tubae, probablydue to the bilateral ovarian activity in this species. Thenon-sulphated GAG HA is also present in the porcineODF and without segmental differences, but with atendency to increase during standing oestrus, becominghighest around ovulation. Especially in the ampullaremains high during metoestrus (Tienthai et al. 2001).Both hyaluronan synthases, hyaluronan-binding proteinsand specific membrane receptors are present in theepithelial lining, particularly in the SR (Tienthai et al.2003a,b), where mucus accumulates before ovulation(Johansson et al. 2000). As mentioned before, GAGs,HA in particular, seem to be involved in sperm survival,capacitation and binding to and release from the SR (seeRodriguez-Martinez 2007).In-vitro development of porcine oocytes hampers stillfrom normal development as indicated by polyspermicfertilization. Apparently it is caused by insufficientmaturation with a deficient formation of cortical granulesand results in constrained ZP-reaction after firstsperm penetration. Such situation was not seen when weexamined in vivo-matured or in vivo-fertilized oocytes,suggesting that either the final maturation inside the preovulatoryfollicle (Bru¨ ssow, unpublished observations)or inside the oviduct is needed for full competence of thenewly ovulated oocytes. The latter seems most relevantconsidering the final maturation of the ZP, as establishedby Funahashi et al. (2000, 2001), implicating theODF involvement in these processes.The ODF is protein-rich and contains several oviductspecific-proteins(OSP) (Buhi et al. 1997; Buhi 2002;Buhi and Alvarez 2003). It supports fertilization andearly embryo development. For example, Wollenhauptand Bru¨ ssow (1995) described a 97 kDa OSP which waspre-dominantly present on days 1–3 after ovulation(6.8–10.3% of the total oviductal protein), and onlyattached to oviduct-derived embryos but not to intrafollicularoocytes or in vitro-derived embryos (Bru¨ ssowet al. 1998b). A contribution of this OSP on embryodevelopment was demonstrated in vitro. Supplementationof the 97 kDa protein increased de novo proteinsynthesis in in vivo matured embryos (Wollenhaupt et al.1997), reduced polyspermic penetration (Kouba et al.2000), and increased cleavage and blastocyst rate(McCauley et al. 2003).However, not only the ODF influences the fate ofgametes in the oviduct, but also oocytes and spermatozoaalter the oviductal secretory proteomic profile. Afterin vitro incubation of porcine oviducts either with boarspermatozoa or COCs, altogether 34 proteins wereregulated by the presence of spermatozoa (n = 20),oocytes (n = 5) or of both gametes (n = 9). Of theseproteins, 18 were up-regulated and 16 were downregulated(Georgiou et al. 2005). With respect to functionalcategories, gene-regulation related to proteinproduction, maintenance and repair (41%), antioxidantsand radical scavengers (18%), metabolism (15%) andmiscellaneous (25%). These changes seem to provide afavourable microenvironment for gametes and preparethe oviduct milieu for embryo arrival.Concluding RemarksAlthough numerous interactions between the Fallopiantube and gametes in pigs are recognized, our knowledgeis yet limited. Attempts have to be made to elucidate thefine tuning of intra-follicular oocyte development andovulation with sperm release and capacitation. Therelationship between gametes within the oviduct andoviductal secretion, and subsequent embryo developmentneeds further research. Increased knowledge aboutthe complex and dynamic processes within the Fallopiantube should additionally improve assisted techniquesincluding in vitro embryo production in swine.AcknowledgementsThe studies of the authors have been made possible by grants from theGerman BMELV, Hungarian OTKA, FORMAS and the SwedishFarmer’s Foundation for Agricultural Research (SLF), Stockholm.ReferencesAlanko M, 1965: The site of recovery and cleavage rate of pigova from the tuba uterina. Nord Vet Med 17, 323–327.Alanko M, 1974: Fertilization and early development of ova inAI-gilts, with special reference to role of tubal spermconcentration. A clinical and experimental study. PhDThesis, University of Helsinki.Andersen D, 1927: The rate of passage of the mammalianovum through various portions of the Fallopian tube. Am JPhysiol 82, 557–569.Austin CR, Walton A, 1960: Fertilisation. In: Parkes AS (ed.),Marshal’s Physiology of Reproduction. 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