Chromosomal aberrations in couples undergoing intracytoplasmic sperm injection: influence on implantation and ongoing pregnancy rates.

OBJECTIVE: To determine the incidence of chromosomal aberrations in couples undergoing intracytoplasmic sperm injection (ICSI) and their influence on subsequent implantation and ongoing pregnancy rates. DESIGN: Prospective study. SETTING: Fertility center. PATIENT(S): Candidates for ICSI. INTERVENTION(S): Chromosomes were trypsin-banded in 2,280 patients. In all cases, 10 metaphases were karyotyped. Sex chromosome analysis was performed in 10 additional metaphases. When apparent chromosomal aberrations were detected, 100 metaphases were analyzed. MAIN OUTCOME MEASURE(S): Implantation and ongoing pregnancy rates in couples with a chromosomal disorder. RESULTS: A chromosomal abnormality was demonstrated in 7.2% of all couples. Among the male partners, 4.48% had aberrations. Autosomal aberrations were present in 2.96%, and numerical or structural sex chromosome abnormalities were found in 1.52%. Among the female partners, numerical or structural abnormalities were documented in 9.79%. Only 2.32% of the female partners had autosomal structural abnormalities. Numerical or structural anomalies involving sex chromosomes were found in 7.47%. Implantation rates of 9.4% and 16.3% per embryo were observed in female partners with sex chromosome mosaicism and autosomal aberrations, respectively. In male partners, the respective rates were 3.8% and 23.1%. CONCLUSION(S): The incidence of chromosomal disorders in couples seeking ICSI treatment is considerable, especially minor mosaicism (<10%) of sex chromosomes in the female partners. Preliminary data indicate a low implantation rate in couples with minor mosaicism of sex chromosomes.

The transport of vitamin C in the isolated human near-term placenta.

We investigated the specific uptake (reference: [H3]-L-glucose) as a measure of membrane transfer of [C14]-labeled L-ascorbic acid (AA), L-dehydroascorbic acid (DHA) and diketogulonic acid using the single injection, double tracer dilution method in the artificially perfused lobe of the near-term human placenta. The uptake of DHA (40-60%) on both the fetal and the maternal side was 3-6 times higher than the uptake of AA, whereas an uptake of diketogulonic acid was not detected. AA transport was slightly higher on the maternal side. Uptake of DHA was suppressed by phloretin and cytocholasin B, whereas AA transfer was not affected. Low sodium concentrations inhibited the uptake of DHA. D-glucose (> 20 mmol/l) inhibited the DHA uptake, and DHA inhibited D-glucose uptake but not L-alanine uptake. The Km value (self inhibition) for DHA was 6-14 mmol/l. Vitamin C enters the trophoblast predominantly as L-dehydroascorbic acid. Its transfer through the microvillous and basal membrane might use the glucose transporter, however, a specific sodium-dependent pathway is not ruled out. Our transfer data suggest an intracellular pool of vitamin C which fills up with increasing plasma DHA-concentrations.