Mechanisms for the Establishment of Pregnancy in the Pig

Abstract

ContentsEstablishment of pregnancy in pigs requires continuous function of corpora lutea and endometrial preparation for embryo implantation. Progesterone regulates expression of many proteins necessary for endometrial remodelling and embryo-maternal communications. Attaining the uterine receptivity involves progesterone priming and loss of progesterone receptors in the uterine epithelium before days 10-12 after oestrus. Spermatozoa and oocytes in oviduct alter secretion of specific proteins that exert beneficial effect on gametes and embryos. Moreover, an appropriate leucocyte activation and maintenance of delicate cytokine balance within the oviduct and uterus are important for early pregnancy. This early local immune response is rather mediated by seminal plasma components. These components also influence prostaglandin (PG) synthesis in the oviduct that is important for gamete and embryo transport. Pregnancy establishment requires the biphasic pattern of oestrogen secretion by conceptuses on days 11-12 and 15-30. Conceptus affects lipid signalling system consisting of prostaglandins and lysophosphatic acid. PG synthesis is changed by conceptus signals in favour of luteoprotective PGE 2 . Additionally, existence of PGE 2 positive feedback loop in the endometrium contributes to increased PGE 2 ⁄ PGF 2a ratio during the peri-implantation period. PGE 2 through endometrial PGE 2 receptor (PTGER2) elevates the expression of enzymes involved in PGE 2 synthesis. Higher PGE 2 secretion in uterine lumen coincides with the elevated expression of HOXA10 transcription factor critical for implantation. A stable adhesion between conceptus and endometrium requires reduction in mucin-1 on the apical surface of epithelium and integrin activation by extracellular matrix proteins. Furthermore, growth factors, cytokines and its receptors are involved in embryo-maternal interactions.

Influence of β2- and β3-adrenoceptor agonists on contractile activity of the porcine myometrium in the luteal phase and the first days of pregnancy

“…The early pregnancy in the pig is divided into three periods: post-conception (days 1-10 of pregnancy), the maternal recognition of pregnancy (days 11-13) and implantation (days 14-19) (Zięcik et al 2011). In our previous study we showed that the presence of embryos increased contractile activity in the porcine myometrium on days 12-14 of pregnancy.…”

The Dog: Nonconformist, Not Only in Maternal Recognition Signaling

“…Furthermore, by inhibiting IL2 and expression of its receptor in human decidua, PGE2 was shown to block activation of maternal leukocytes with potential anti-trophoblast function, thereby revealing an immunosuppressive but embryo-protective effect (Parhar et al 1989 ). The embryo-and luteo-protective role of endometrial PGE2 has been discussed for pigs, in which additionally, speciesspecifi cally, estrogen also increases PGE2 secretion (see review Ziecik et al 2011 ). Similar effects could also apply to the canine species as suggested by the concomitantly and abundantly expressed PTGES levels in hatched compared to unhatched preimplantation embryos (Kautz et al 2014 ).…”

032 Use of Triptorelin Acetate for Inducing Ovulation and Facilitating Fixed Time Artificial Insemination of Sows Weaned on Small-Scale and Niche Market Pig Farms

“…If not, PGF2α will be secreted by uterine capillaries, causing luteolysis (Senger, 1997). At the time of maternal recognition of pregnancy blastocytes will undergo a morphological transformation from a spherical to filamentous shape 10 mm in diameter around d 11.5 (Geisert et al, 1982;Ziecik, 2011). The elongation of filamentous forms will exceed 60 to 100 cm and complete this process by d 13 (Anderson, 2009).…”