The most important risk factor for human aneuploidy is increasing maternal age, but the basis of this association remains unknown. Indeed, one of the earliest models of the maternal-age effect--the "production-line model" proposed by Henderson and Edwards in 1968--remains one of the most-cited explanations. The model has two key components: (1) that the first oocytes to enter meiosis are the fi...

In mice and humans, a normal offspring can be obtained by injecting a single spermatozoon into an oocyte, the process called intracytoplasmic sperm injection (ICSI). When three or more mouse spermatozoa with intact acrosomes were injected into individual mouse oocytes, an increasing proportion of oocytes became deformed and lysed. Oocytes did not deform and lyse when acrosome-less spermatozoa w...

During meiosis in human oocytes, chromosome nondisjunction increases with maternal age, leading to disorders such as Down's syndrome. In a recent study in Nature Genetics, Hodges et al. (2005) show that mice with a mutation in the meiosis-specific cohesin protein SMC1beta exhibit age-dependent defects in meiosis. These defects are similar to those observed in oocytes of older human mothers. The...

Background: Polycystic ovary syndrome (PCOS) is a frustrating experience for women, considered as a complex challenge for researchers and clinicians. Despite the enormous effort to define the cause of PCOS, the etiology and pathogenesis still remain unclear. Oocyte quality is reflected in the oocyte’s intrinsic developmental potential. Studies have shown that the follicular development is disru...

Previous work from our laboratory demonstrated the existence of miRNAs in human follicular fluid. In the current study, we have sought to identify miRNAs that might affect oocyte/embryo quality in patients undergoing intracytoplasmic sperm injection and to investigate their roles in in vitro fertilization outcomes in mouse oocytes. 53 samples were classified as Group 1 (high quality) if the day...

BACKGROUND With improved prospects for the use of human oocyte in-vitro maturation in assisted reproductive technologies, the need to define more clearly the coordination of nuclear and cytoplasmic maturation has arisen. METHODS Immunofluorescence and confocal microscopy were used to evaluate cell cycle-dependent modifications in chromatin and microtubules in human germinal vesicle oocytes (n...

OBJECTIVE To determine the effect of infertility-linked sperm phospholipase Cζ (PLCζ) mutations on their ability to trigger oocyte Ca(2+) oscillations and development, and also to evaluate the potential therapeutic utility of wild-type, recombinant PLCζ protein for rescuing failed oocyte activation and embryo development. DESIGN Test of a novel therapeutic approach to male factor infertility....

The Xenopus oocyte is a very powerful tool for studies of the structure and function of membrane proteins, e.g., messenger RNA extracted from the brain and injected into oocytes leads to the synthesis and membrane incorporation of many types of functional receptors and ion channels, and membrane vesicles from Torpedo electroplaques injected into oocytes fuse with the oocyte membrane and cause t...

Background Effect of seasonal changes in human reproduction has been intensively researched. Some studies acknowledge influences of seasonal variation on natural conception, while others can not confirm them. The aim of this study was to investigate the effect of seasonal changes on different stages of assisted reproductive technology (ART) in Tehran. MaterialsAndMethods This study was carried ...

RIC-3 enhances the functional expression of certain nicotinic acetylcholine receptors (nAChRs) in vertebrates and invertebrates and increases the availability of functional receptors in cultured cells and Xenopus laevis oocytes. Maximal activity of RIC-3 may be cell-type dependent, so neither mammalian nor invertebrate proteins is optimal in amphibian oocytes. We cloned the X. laevis ric-3 cDNA...