Fertilization in vivo is a complex process consisting of six steps, namely, penetration of the cumulus complex, binding of the sperm to the zona pellucida, fusion of oocyte and sperm, oocyte activation, sperm remodelling, and formation of the pronuclei. Since ICSI bypasses the first three steps any problem related to fertilization failure after ICSI arises from oocyte activation onwards. Accord...

BACKGROUND Sperm-oocyte fusion is a critical step in fertilization, which requires a series of proteins from both spermatozoa and oocyte to mediate membrane adhesion and subsequent fusion. A rat spermatozoa membrane protein is endoplasmic reticulum protein 29 (ERp29), which significantly increases on the sperm surface as well as in the cytoplasm of epididymal epithelia from caput to cauda as th...

Oogenesis in Drosophila is a useful model for studying cell differentiation. We have analyzed the role of the egh gene in these processes with the aid of a newly isolated viable but female sterile allele. This mutation results in diverse variable defects in oogenesis. The most frequent defect being follicles that have either more or less than the normal number of 16 germ cells. This is caused b...

Most current studies of nuclear transfer in mammalian oocytes have used electrofusion to incorporate donor cell nuclei into enucleated oocyte cytoplasts. However, the application of electrofusion to human oocytes is hampered by the relative ease with which this procedure induces oocyte activation. Here we tested a previously described chemical fusion technique and an original mechanical fusion ...

The ability of human spermatozoa to exhibit sperm-oocyte fusion in response to the ionophore, A23187, was examined in relation to the capacity of these cells to generate reactive oxygen species. In 70 fertile control donors, there was an overwhelming pattern of high levels of sperm-oocyte fusion associated with low levels of reactive oxygen species production. By contrast, 88% of the 74 oligozo...

Since the pig is not only an important farm animal, but also a model animal for biomedical applications, the development of reproductive technologies in this species has been very important. In vitro oocyte maturation and fertilization (IVM-IVF) are basic techniques for a number of oocyte- or embryo-related technologies. The practical aspects for pig oocyte IVM-IVF have been reviewed, while the...

When a sperm and an oocyte unite upon fertilization, their cell membranes adhere and fuse, but little is known about the factors regulating sperm-oocyte adhesion. Here we explored the role of β-catenin in sperm-oocyte adhesion. Biochemical analysis revealed that E-cadherin and β-catenin formed a complex in oocytes and also in sperm. Sperm-oocyte adhesion was impaired when β-catenin-deficient oo...

With the help of the technique of Sendai virus-mediated cell fusion, hybrid cells were produced between two maturing oocytes, between maturing oocytes or mature secondary oocytes and interphase blastomeres from 2-cell embryos, and between secondary oocytes and follicle cells (FC). In the first case giant oocytes form and in these the two groups of condensing bivalents join on a common spindle, ...

Polarization of the microtubule cytoskeleton is an early event in establishment of anterior-posterior polarity for the Drosophila oocyte. During stages 8-9 of oogenesis, when oskar mRNA is transported to the posterior pole of the oocyte, a fusion protein consisting of the plus-end-directed microtubule motor kinesin and beta-galactosidase (Kin:beta gal) similarly localizes to the posterior pole,...

The interaction of preincubated ram sperm with zona-free hamster oocytes was studied by scanning and transmission electron microscopy. The behaviour of the sperm cells was quite different, depending on whether the acrosomal reaction had taken place or not. The apical ridge of intact spermatozoa contacted the oocyte surface, and egg microvilli spread onto the anterior segment but no fusion ensue...