Heterogeneity of the zona pellucida carbohydrate distribution in human oocytes failing to fertilize in vitro

Abstract

The mammalian zona pellucida contains several glycoproteins whose oligosaccharide moieties are known to play a key role in the interaction with spermatozoa. Since zona pellucida defects may represent one of the most likely causes of failed fertilization in human in-vitro reproduction, we have studied the carbohydrate composition and distribution over the human zona pellucida by means of lectins. Donated, not inseminated cumulus-oocyte complexes, from cohorts with high fertilization rates, and fertilization-failed oocytes from cohorts inseminated with proven fertile donor semen, were analysed using 11 fluorescein-labelled lectins, on deplasticized semi-thin epoxy sections. Results showed that wheat germ agglutinin (WGA), Maclura pomifera (MPA) and Pisum sativum (PSA) bound to the extracellular matrix bordering the zona pellucida-corona radiata interface of cumulus-oocytes complexes, while the zona pellucida was labelled by WGA, Concanavalin A (ConA) and PSA. WGA labelling and correlative electron microscopy on the cumulus-oocyte complexes demonstrated that this lectin is a useful tool to trace the cortical granule distribution in the human oocyte. Surprisingly, in the failed-fertilized oocytes the zona pellucida was also labelled by MPA and showed three different patterns: (i) labelling of the zona pellucida outer surface; (ii) uniform labelling; (iii) labelling of an outer zona pellucida layer with variable thickness. Comparative analysis of WGA and MPA labelling on single failed-fertilized oocytes demonstrated that MPA zona pellucida patterns are not related to the cortical reaction. The nature and meaning of the MPA pattern of failed-fertilized oocytes were discussed in the light of zona pellucida defects impairing sperm receptivity.

Dachsous1b cadherin regulates actin and microtubule cytoskeleton during early zebrafish embryogenesis

“…We next labeled CGs in fixed eggs using fluorescent dye-conjugated Maclura pomifera agglutinin (MPA) (Becker and Hart, 1999;Dosch et al, 2004;Mei et al, 2009;Talevi et al, 1997). At 1 min post activation (mpa), CGE in WT and Mdchs1b eggs were comparable.…”

Ultrastructural markers of quality are impaired in human metaphase II aged oocytes: a comparison between reproductive and in vitro aging

“…Morphofunctional studies of human MII oocytes aged in culture show contradictory result: Ducibella et al [61] found an occurrence of CG exocytosis and consequent zona hardening, while Talevi et al [62] showed an intrinsic alteration in ZP with no alteration of CG distribution. Our results underline an abnormal reduction in amount (and inner density in some cases) of suboolemmal CG in all aged samples, when compared with those of fresh controls.…”

Cortical granule exocytosis inC. elegansis regulated by cell cycle components including separase

“…S1A-F in the supplementary material). Wheat germ agglutanin (WGA), used to identify cortical granules in human oocytes (Talevi et al, 1997), labeled 1 m vesicles in C. elegans oocytes and meiosis I embryos, but not in older embryos ( Fig. 1A-C).…”