Search

The spindle assembly checkpoint suspends cell cycle progression if improperly aligned chromosomes are detected at metaphase. Evolutionarily conserved kinetochore-associated proteins are believed to be key elements of this regulatory pathway. A breakdown in checkpoint function could bring about genomic instability, which may be responsible for the prevalence of aneuploidy in oocytes of older women. Maternal aging remains the overwhelming factor in the etiology of human aneuploidy in assisted reproduction. Defects in cell cycle checkpoint genes may play a role in its development. The existence of such monitoring mechanisms in oocytes has long been controversial. Studies providing evidence in support of and against their existence are reviewed. Copyright © 2005 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

A study was conducted on patients who had attempted and failed previous in-vitro fertilization (IVF) procedures an average of 3.8 times following the application of assisted hatching with conventional culture systems. The aim of this investigation was to determine if addition of co-culture methodologies could reduce embryonic abnormalities and thus improve the prognosis for pregnancy. The study population consisted of 123 patients, subdivided into three patient categories. Previous IVF results from conventional culture were used to evaluate any potential benefits derived from the present co-culture application. Following co-culture, the rate of blastomere development was increased and the rate of fragmentation decreased. An increased rate of blastomere development was most noticeable in the patients aged < or = 39 years with no male factor as well as the intracytoplasmic sperm injection (ICSI) subgroup. Similarly, the rate of fragmentation was significantly reduced in the aforementioned subgroups. The most pronounced impact of co-culture was on pregnancy and implantation rates. The overall clinical and ongoing pregnancy rates were 38% (47/123) and 36% (44/123) respectively. The corresponding implantation rate was 17% (72/ 412) as shown by embryonic cardiac activity. The ongoing pregnancy rates in the < or = 39 years no male factor, > or = 40 years no male factor and ICSI no age limit patient subgroups were 41% (21/51), 30% (8/27) and 33% (15/45) respectively. The results indicate that addition of co-culture to the IVF procedure for poor-prognosis patients may be advisable. [ABSTRACT FROM AUTHOR]

A study was conducted on patients who had attempted and failed previous in-vitro fertilization (IVF) procedures an average of 3.8 times following the application of assisted hatching with conventional culture systems. The aim of this investigation was to determine if addition of co-culture methodologies could reduce embryonic abnormalities and thus improve the prognosis for pregnancy. The study population consisted of 123 patients, subdivided into three patient categories. Previous IVF results from conventional culture were used to evaluate any potential benefits derived from the present co-culture application. Following co-culture, the rate of blastomere development was increased and the rate of fragmentation decreased. An increased rate of blastomere development was most noticeable in the patients aged ≤39 years with no male factor as well as the intracytoplasmic sperm injection (ICSI) subgroup. Similarly, the rate of fragmentation was significantly reduced in the aforementioned subgroups. The most pronounced impact of co-culture was on pregnancy and implantation rates. The overall clinical and ongoing pregnancy rates were 38% (47/123) and 36% (44/123) respectively. The corresponding implantation rate was 17% (72/412) as shown by embryonic cardiac activity. The ongoing pregnancy rates in the ≤39 years no male factor, ≥40 years no male factor and ICSI no age limit patient subgroups were 41% (21/51), 30% (8/27) and 33% (15/45) respectively. The results indicate that addition of co-culture to the IVF procedure for poor-prognosis patients may be advisable. [ABSTRACT FROM PUBLISHER]

A retrospective study was undertaken to determine if initial culture conditions and embryo quality had an effect on subsequent blastocyst development in co-culture for cryopreservation. The apparent effects of freeze–thawing on blastocysts at the ultrastructure level were also observed. On day 3 of culture, embryos were categorized into two groups based on their morphological attributes. Results suggest that the initial culture environment of embryos up to day 3 (5- to 8-cell stage) did not affect the subsequent rate of blastocyst formation in co-culture. However, the initial embryo quality had an impact on blastocyst formation and quality. On day 5.5, 90% (60/67) of the optimal quality embryos (six to eight blastomeres with minimal or no fragmentation on day 3) had attained the blastocyst stage, which was greater ( < 0.01) than the 55% (31/56) observed with the sub-optimal embryos (five to eight blastomeres with 30–50% fragmentation on day 3). Furthermore, 66% (44/67) of embryos initially graded as optimal were suitable for cryopreservation, which was greater ( < 0.01) than attained with embryos of lesser quality (22/56; 39%). At the ultrastructural level, the polarized distribution of plasma membrane microvilli was retained, as was the integrity of the nuclear membrane following thawing.co-culture [ABSTRACT FROM PUBLISHER]

Videocinematography and image analysis procedures were utilized to evaluate the effect of conventional and coculture methodologies on morphological parameters in human embryos derived from in-vitro fertilization (IVF). Following 24–30 h of in-vitro development, cocultured embryos had more acceptable morphological features and less fragmentation present than embryos cultured in medium alone. Cocultured embryos were more advanced at the time of replacement when compared with conventionally cultured embryos. Zona pellucida variation (≥20%) also occurred more frequently in cocultured embryos. The morphological characteristic most enhanced after coculture was blastomere expansion. Patients who became pregnant across both culture treatments had a higher proportion of morphologically normal embryos replaced than patients who failed to achieve an ongoing pregnancy. Clinical pregnancy rate for patients following coculture was 49%, which was greater ( < 0.05) than the 29% detected for patients with embryos in the conventional culture group. [ABSTRACT FROM PUBLISHER]