background: human menopausal gonadotropin (hmg) has contributed many improvements to human assisted reproduction. however, effects of hmg on oocyte development and clinical results remain controversial. objective: this study was conducted to investigate the effects of hmg on the zona pellucida of oocytes, as well as clinical results in superovulation treatment. materials and methods: this retro...

Background: The potential applications of a simplified method of somatic cell nuclear transfer (SCNT) that is improved in both efficiency and throughput is considerable. Technically, a major step of SCNT is to produce large pools of enucleated oocytes (cytoplasts) efficiently, a process that requires considerable micromanipulation skill and expensive equipment. Here, we have devel oped an efficient...

As the demand for cloned embryos and offspring increases, the need arises for the development of nuclear transfer procedures that are improved in both efficiency and ease of operation. Here, we describe a novel zona-free cloning method that doubles the throughput in cloned bovine embryo production over current procedures and generates viable offspring with the same efficiency. Elements of the p...

The mammalian zona pellucida is an extracellular matrix that occurs in growing oocytes, ovulated eggs and pre-implantation embryos, and is known to be involved in several important events during ovarian folliculogenesis and fertilization. Since the zona pellucida is formed at an early stage of oocyte growth, circulating antibodies against zona pellucida may impair ovarian function. In this arti...

Mammalian oocytes synthesize and secrete a zona pellucida that surrounds the growing oocytes, ovulated eggs and preimplantation embryos. The extracellular zona matrix is composed of three glycoproteins (ZP1, ZP2, ZP3) that are involved in folliculogenesis, species-specific fertilization, and passage of the early embryo down the oviduct. We have established a mouse line in which Zp3 has been ina...

The sperm acrosome reaction takes place in response to progesterone and zona pellucida. Progesterone may act on more than one type of surface receptor, of which one is a gamma-aminobutyric acid (GABA) type A-like receptor. Although there is direct evidence of GABA initiation of mouse sperm acrosome reaction, there are conflicting results regarding GABA-induced exocytosis in human spermatozoa. W...

Knowledge about the mechanism that establishes embryonic polarity is fundamental in understanding mammalian development. In re-addressing several controversial claims, we recently proposed a model in which mouse embryonic polarity is not specified until the blastocyst stage. Before fertilization, the fully differentiated oocyte has been characterized as "polarized," and we indeed observed that ...

Carbohydrate-protein interactions are known to be important in gamete interactions. Several evidence indicated that a fucose-containing sulfated polysaccharide fucoidan was potential inhibitor of fertilization in vitro and thus fucose seemed to be part of the recognition signal of gamete interaction in mammals. In recent investigation we found that α-L-fucosidase activity was present in boar sp...

Carbohydrates are candidates for the basis of species-selective interaction of gametes during mammalian fertilization. In this study, we sought to clarify the roles of sugar residues in the species-selective, sperm-oocyte interaction in pigs and cattle. Acrosome-intact porcine and bovine sperm exhibited their strongest binding affinities for β-Gal and α-Man residues, respectively. Porcine-sperm...