BACKGROUND In mammalian follicles, oocytes are arrested at the diplotene stage of prophase I until meiotic resumption following the LH surge. Recently, C-type natriuretic peptide (CNP), encoded by natriuretic peptide precursor type C (NPPC) was found to suppress mouse oocyte maturation by promoting cyclic guanosine 5'-monophospate (cGMP) production in cumulus cells. However, regulation of NPPC/...

Intracellular regulation of oocyte meiosis is not completely understood. However, reversible phosphorylation, which involves serine/threonine protein kinases and phosphatases (PP), is an important mediator. Glycogen synthase kinase-3 (GSK-3) is a highly conserved serine/threonine protein kinase. Currently no reports exist on presence or function of GSK-3 in mammalian oocytes. The aim of this st...

Studies were carried out to identify and quantify the porcine follicular fluid (PFF) component(s) responsible for inhibition of murine oocyte maturation. A low molecular weight fraction of PFF (less than 1000) was prepared by dialysis and used in all experiments. This PFF fraction contained an inhibitor(s) of mouse oocyte maturation that absorbed maximally in the ultraviolet (UV) range at 250-2...

Oocyte-specific genes play important roles in regulating ovarian development, principally through the proper and timely progression of oogenesis and folliculogenesis. Development of transgenic mouse models has been critical in revealing how oocyte-specific transcripts influence oocyte development and growth, integrity of the oocyte-granulosa cell complex, oocyte maturation, fertilization, and e...

In a total of 1048 intracytoplasmic sperm injection (ICSI) cycles, motile spermatozoa from four out of 424 patients (0.9%) failed to fertilize oocytes, despite an apparently successful ICSI procedure. No activation was observed in these injected oocytes. The spermatozoa from three of the four patients were injected into unfertilized mouse oocytes by ICSI (mouse test) to evaluate their oocyte ac...

Resumption of meiosis was inhibited in mouse oocyte cumulus complexes (OCC) co-cultured with pig membrane granulosa (PMG). After 3 and 6 h of co-culture these oocytes possessed an intact nuclear envelope and their nucleolar surface was associated with granules approximately 80 nm in diameter. Preincubation of OCCs for 30, 45, 60 or 90 min followed by co-culture with PMG for 2 h of either OCCs o...

Chromosome segregation in mammalian oocyte meiosis is an error-prone process, and any mistake in this process may result in aneuploidy, which is the main cause of infertility, abortion and many genetic diseases. It is now well known that shugoshin and protein phosphatase 2A (PP2A) play important roles in the protection of centromeric cohesion during the first meiosis. PP2A can antagonize the ph...

The main objective of the present study was to identify novel oocyte-specific genes in three different species: bovine, mouse, and Xenopus laevis. To achieve this goal, two powerful technologies were combined: a polymerase chain reaction (PCR)-based cDNA subtraction, and cDNA microarrays. Three subtractive libraries consisting of 3456 clones were established and enriched for oocyte-specific tra...