Marijke Bras

Triploidy after in vitro fertilization: cytogenetic analysis of human zygotes and embryos.

Tripronuclear zygotes obtained from a clinical IVF program were studied cytogenetically. Successful analysis was possible of 42 specimens at the zygote stage and 21 embryos after the first or second cleavage division. In the majority of zygotes (88%) the expected triploidy was confirmed, whereas only 14% of embryos had solely triploid cells. Therefore it is concluded that after tripolar cleavage division, many different types of mosaicism may originate from irregular chromosome distributions. Since the findings in individual blastomeres in embryos resulting from multipronuclear zygotes do not reflect the genetic content of the whole embryo, these embryos are less suitable in a model system for preimplantion diagnosis. The distribution of the sex chromosomal types (XXX, XXY, and XYY) confirmed theoretical expectations. Since in abortion material or in liveborn triploidy cases, the XYY karyotype is hardly ever observed, this indicates that most likely the 69,XYY karyotype has a very high embryonic mortality.

Immaturity and aneuploidy in human oocytes after different stimulation protocols

OBJECTIVE To study immaturity and aneuploidy in human oocytes after two different stimulation protocols. DESIGN Retrospective. SETTING Outpatient IVF clinic/laboratory. PATIENTS One hundred forty-three patients of whom 65 were stimulated with clomiphene citrate (CC)/human menopausal gonadotropin (hMG) and 78 were stimulated with gonadotropin-releasing hormone agonist (GnRH-a)/hMG. Only patients with at least one oocyte unfertilized were included in this study. RESULTS Stimulation with GnRH-a/hMG, as compared with CC/hMG stimulation, resulted in larger numbers of oocytes (P less than 0.00001), a higher fertilization rate (P less than 0.02), and oocyte retrieval at a later average cycle day (P less than 0.000005). Cytogenetic findings of immaturity were observed in 33.9% of unfertilized oocytes after CC/hMG stimulation, compared with only 17.8% after GnRH-a/hMG stimulation (P less than 0.0005). Aneuploidy findings were the same for both groups. CONCLUSION In GnRH-a/hMG stimulation, oocytes approach the normal day of ovulation more closely. This may allow for better oocyte maturation and higher fertilization and pregnancy rates.

Allelic dropout caused by allele-specific amplification failure in single-cell PCR of the cystic fibrosis ΔF508 deletion

Allelic Dropout Caused by Allele-Specific Amplification Failure in Single-Cell PCR of the Cystic Fibrosis AF508 Deletion* can make a reliable distinction between a homozygous wild-type (WT) and a homozygous AF508 genotype at the single-cell level in the cystic fibrosis AF508 PCR system. Furthermore, in heterozygotes the allelic dropout frequency by allele specific amplification failure will be determined. An allelic dropout rate of 25% has been reported (3). Finally, we wish to determine the total amplification failure for all genotypes.

Human in vitro Fertilization Using Spermatozoa Capacitated in Hyperosmotic Media

In two separate prospective randomized series of 38 and 16 attempts of human in vitro fertilization (IVF), respectively, the fertilizing abilities of human spermatozoa capacitated in hyperosmotic media and in normosmotic medium were compared. Oocytes from each IVF attempt were divided into two equal groups and inseminated with spermatozoa incubated for 2 h in medium with an osmolality of 285 mosm/kg or in hyperosmotic medium of 315 (first experiment) or 345 mosm/kg (second experiment). The fertilizing capacity of the spermatozoa was not affected by incubation in medium of 315 mosm/kg as compared to spermatozoa incubated in medium of 285 mosm/kg. However, the fertilizing capacity of the spermatozoa incubated in medium of 345 mosm/kg was significantly reduced. The present study indicates that there is no advantage in the use of hyperosmotic media of 315 or 345 mosm/kg for capacitation of spermatozoa in human IVF.