Oviduct function in pigs, with particular reference to the pathological condition of polyspermy

Abstract

Because the exceptionally high incidence of polyspermic fertilisation has been emphasised as a major defect in systems of in vitro fertilisation in pigs, the aetiology of the condition has been analysed in a series of experiments in vivo in the search for a common underlying cause and possible means of mitigation. Whereas the defense mechanism against polyspermy in pig oocytes is classically viewed as a zona reaction, more recent evidence suggests a secondary block at the vitelline surface. Both blocks may be compromised in situations leading to polyspermy, although deleterious influences seem to be expressed principally in an inadequate zona block, as judged by the presence of perivitelline spermatozoa.Postovulatory aging of mammalian oocytes prior to sperm penetration leads to polyspermy, as can be demonstrated in pig eggs. The primary lesion may concern the cortical reaction, owing to a delayed and incomplete exocytosis of the vesicular contents. Eggs ovulated after gonadotrophin treatment during the luteal phase of the cycle show a high incidence of polyspermic penetration (60.6%), as do those shed at estrus in animals treated with progesterone systemically (40%) or by local microinjections in the oviduct wall (32.3%). Whereas progesterone may be modifying interactions of the gametes and responses of the egg organelles in all four above experimental situations, enhanced numbers of spermatozoa ascending a more patent isthmus appear to be the principal cause of polyspermy. Support for this hypothesis comes from isthmus resection with re-anastomosis of remaining portions of the oviduct (32.4% polyspermy), and surgical insemination directly into the oviducts (33.8% polyspermy). Recent experiments draw attention to a role for oviduct epithelial glycoproteins in modulating the extent of polyspermy in vitro. The role of such oviduct macromolecules in gamete interactions in vivo is considered.

In vitro fertilization and polyspermy in the pig: Factors affecting fertilization rates and cytoskeletal reorganization of the oocyte

“…In the pig, polyspermy is dependent on different boars (Sirard et al, 1993;Wang et al, 1991) and on the presence of a high concentration of capacitated spermatozoa during fertilization (Hunter, 1991;Kim et al, 1997a). Xu et al (1996) reported, based on fresh semen from 3 boars of different breeds, that boars and sperm concentration affect the rates of penetration, polyspermy, and male PN formation.…”

“…Polyspermic fertilization occurs more frequently in the pig than in the other species, even for in vivo fertilization under diverse experimental conditions (Hunter, 1967(Hunter, , 1990(Hunter, , 1991. Although techniques for achieving in vitro maturation and in vitro fertilization (IVF) of pig oocytes have been progressively improved in recent years, a high incidence of polyspermy is still one of the major problems in the pig IVF program (Abeydeera, 2001;Nagai and Moor, 1990;Niwa, 1993;Yoshida et al, 1990).…”

Oviduct-specific glycoprotein and heparin modulate sperm–zona pellucida interaction during fertilization and contribute to the control of polyspermy

“…P olyspermy (the penetration of the egg cytoplasm by more than one spermatozoa) is a pathologic condition in placental mammals, usually causing early death of the embryo (1). Although the prevalence of polyspermy under natural conditions is moderate, in in vitro fertilization (IVF) systems polyspermy remains a major obstacle to successful development of viable embryos in different species, including humans (2).…”

“…Many studies support a functional role for the oviduct and its secretions (which are rich in estrus-associated glycoproteins) in fertilization, regulating processes such as sperm-ZP binding, the establishment of species-specific ZP barriers, and early embryonic development (1,10,13,(18)(19)(20)(21). However, the molecular mechanisms underlying oviductal regulation are not fully understood, and few studies on this topic have been conducted with domestic ungulates as models.…”

Expression of 3β-hydroxysteroid dehydrogenase and P450 aromatase in porcine oviduct during the oestrous cycle

“…Steroid hormones, mainly progesterone (P4) and oestradiol-17β (E2), affect oviduct functioning in pigs and other species (Hunter, 1991(Hunter, , 2012Hunter et al, 1999;Chen et al, 2013). These steroids affect gene expression, cells ultrastructure and differentiation, motility of oviduct, as well as the composition and volume of oviductal fluid during the oestrous cycle (Rodriguez-Martinez et al, 1982;Buhi, 2002;Yaniz et al, 2006;Carrasco et al, 2008;Skowronski et al, 2011;Hunter, 2012).…”