OBJECTIVE The goal of this study was to evaluate the pregnancy potential of immature (metaphase I or germinal vesicle stage) oocytes retrieved in intracytoplasmic sperm injection (ICSI) cycles. METHODS A total of 1,871 couples with infertility underwent 2,984 ICSI cycles. Cycles in which three or fewer oocytes were retrieved were included in this study in order to evaluate the pregnancy poten...

In the mammalian oocyte, distinct patterns of centromeres and pericentromeric heterochromatin localisation correlate with the gamete's developmental competence. Mouse antral oocytes display two main types of chromatin organisation: SN oocytes, with a ring of Hoechst-positive chromatin surrounding the nucleolus, and NSN oocytes lacking this ring. When matured to MII and fertilised, only SN oocyt...

We examined the relationship among morphological appearance (six groups) of bovine oocytes, ATP content and maturational/developmental ability. Oocytes with a brown ooplasm (with or without a dark region) had intermediate levels of ATP at the germinal vesicle (GV) stage and showed higher rates of first polar body (PB) extrusion than the other groups. Oocytes with a low level of ATP (oocytes wit...

Background When gonadal sex reversal occurs in mammalian species, the resultant XX males and XY females become infertile or subfertile, suggesting critical roles of sex chromosomes in germ cell differentiation. The objective of our study is to clarify the mechanism of infertility in the B6.YTIR (XY) sex-reversed female mouse, which can be attributed to a failure in the second meiotic division i...

Background: Oocyte cryopreservation is of utmost importance in the current repertories of assisted reproductive technology (ART). Despite this, oocyte vitrification is yet a problematic issue with limited successful pregnancies has been arisen after transfer of embryos derived from vitrified-warmed oocytes. In this sense, great attention has been paid to investigate possible mechanisms underlyi...

To date, production of cloned rats by somatic cell nuclear transfer (NT) has not yet been successful. Inducing premature chromosome condensation (PCC) of injected cell nuclei in recipient cytoplasm is considered essential for successful mouse cloning by the Honolulu method. In the present study, some factors affecting PCC of rat cumulus cell nuclei injected into rat oocytes were examined. Wista...

Careful genetic management, including cryopreservation of genetic material, is central to conservation of the endangered Mexican gray wolf. We tested a technique, previously used to vitrify human and domestic animal oocytes, on oocytes from domestic dogs as a model and from the endangered Mexican wolf. This method provided a way to conserve oocytes from genetically valuable older female Mexican...

The objective of this study was to clarify the effects of prematurational culture (pre-IVM) supplemented with 3-isobutyl-1-methylxanthine (IBMX) on nuclear and cytoplasmic maturation of in vitro-grown bovine oocytes. In experiment 1, oocytes (95 μm in diameter) derived from early antral follicles (0.5–1 mm in diameter) were cultured for 12 days for in vitro growth (IVG). IVG oocytes with a norm...

STUDY QUESTION Does the position of the germinal vesicle (GV) in human oocytes correlate with molecular and morphological parameters as well as with maturation-competence? SUMMARY ANSWER The position of GV in human oocytes correlates with density of microtubule (MT) filaments, concentration of Fyn, nucleolus localization and the ability of the oocytes to complete maturation following GV break...

The effects of in vitro-growth (IVG) culture duration (12 and 14 days) on the fertilizability and the developmental ability of IVG oocytes matured with pre-maturational culture, and on the proliferation of cells surrounding oocytes during IVG culture were examined. The fertilization and cleavage rates of 12- and 14-day IVG oocytes were similar; however, 14-day IVG oocytes showed lower blastocys...