Biomedical subjects

E Macas

Publications and source records attributed to E Macas.

22 records · Page 2Linked to original sources

PubMed1991

Developmental capacities of two-cell mouse embryos frozen by three methods.

The following three methods were evaluated in order to obtain a most efficient freezing protocol for the preservation of two-cell mouse embryos: (a) slow cooling and slow thawing in 1.5 M dimethyl sulfoxide, (b) slow cooling and fast thawing in 1.5 M propanediol (PROH), and (c) ultrarapid freezing and fast thawing in either 3.5 M DMSO or 3.0 M PROH. In the slow-cooling procedures (a and b) ice nucleation (seeding) was induced manually or automatically. With method a, only a slight difference, 51.8% for manual and 58.9% for automatic seeding, was observed in survival rates, while the development to blastocysts was significantly affected: 35.4% with manual and less than 10% with automatic induction (P less than 0.001). Method b gave high survival (86.2%) and developmental rates (69.0%) with manual seeding compared with automatic seeding (20.7 and 9.8%, respectively; P less than 0.001). Using protocol c, higher survival and developmental rates were obtained with DMSO (84.8 and 55.9%) than with PROH (39.8 and 19.4%, P less than 0.001). These results demonstrate that inducing nucleation manually is superior to the use of a highly sophisticated autoseeding system and that method b with manual seeding is most effective in preserving the developmental capacity of two-cell mouse embryos after freezing and thawing. There is evidence that this is also true of human embryo cryopreservation.

Animals↗

PubMed1990

Abnormal chromosomal arrangements in human oocytes.

Ninety-one human oocytes, lacking signs of fertilization 50 h after insemination in vitro, were investigated cytogenetically to assess the frequency and type of chromosomal abnormalities. Chromosome spreading permitted adequate karyotyping in 55 oocytes. Non-determined numerical aberrations occurred with the following frequencies: hypohaploidy, 10.9% (6/55), hyperhaploidy, 14.5% (8/55) and hyperdiploidy, 3.6% (2/55). Total aneuploidy occurred with a frequency of 29.1% and was observed in oocytes from 30 patients. No correlation was found between specific chromosomal aberrations and type of infertility, stimulation treatment or gonadotrophin levels. On the other hand, the frequency of aneuploidy was significantly higher (P less than 0.05) in patients greater than 35 years of age. Two chromosomal complements (3.6%) had structural rearrangements; one oocyte had both structural and numerical chromosomal abnormalities and the other had differently condensed regions on the long arms of three chromosomes from group C. The overall frequency of chromosomal aberrations was 32.7%. Only two samples contained an additional set of polar body chromosomes. Thirteen oocytes presented sperm chromosomes in an arrested stage of premature chromosome condensation of the G1 phase and four oocytes showed asynchronous condensation of pronuclear chromosomes. Finally, it was concluded that the high proportion of chromosomal aberrations observed in human oocytes may contribute significantly to abnormal embryonic development in vitro.

Adult↗

PubMed1988

Prostaglandin F2 alpha, progesterone and estradiol concentrations in human follicular fluid and their relation to success of in vitro fertilization.

Prostaglandin F2 alpha (PGF2 alpha), progesterone (P4) and estradiol-17 beta (E2) in follicular fluid were measured by radioimmunoassay in patients undergoing in vitro fertilization and embryo transfer. Follicular growth was induced using clomiphene citrate-hMG-hCG (15 patients) and FSH-hMG-hCG (4 patients). There was no significant difference in follicular fluid PGF2 alpha and P4 concentrations relative to oocyte maturity as assessed morphologically. The highest PGF2 alpha concentration was found in fluid from FSH-hMG-hCG cycles where fertilization occurred. The value is significantly higher (p less than 0.002) than in fluid from clomiphene-hMG-hCG cycles whether fertilization took place or not. There was no significant difference in P4 and E2 levels in relation to the type of ovarian induction or success in fertilization. Positive correlation between P4 and E2 in follicular fluid was found (r = 0.404). The positive correlation between total dose of hMG given to the patients and PGF2 alpha concentration in their preovulatory follicular fluid (r = 0.434) suggests that PGF2 alpha is secreted locally as the result of hMG and hCG stimulation. It is proposed that PGF2 alpha could be a biochemical marker for assessing the success of in vitro fertilization.

Adult↗

PubMed1988

Chromosomal preparations of human triploid zygotes and embryos fertilized in vitro.

Forty-eight zygotes with more than two pronuclei were identified after in vitro fertilization, representing 6.1% of all fertilized oocytes. The chromosome preparations from pronuclear stage to the cleaved human embryos were examined. Prophase was found in eight out of ten zygotes. The spreading of chromosomes allowed an adequate counting in only two cases. Six of the eight preparations displayed a late prophase. In this stage each haploid group of chromosomes can be analysed separately. Kariogamy usually occurred 4 to 5 h after the pronuclei had disappeared, and polyploid number of chromosomes were found in well-spread metaphases. The chromosomal preparations were made for eleven human embryos arising from zygotes with three pronuclei. Out of ten preparations, where the chromosomes could be counted, seven embryos (70%) contained hypodiploidic groups of chromosomes. In two of the cases, however, triploid metaphases were found, and in the last one a triploid/diploid mosaicism.

Embryo, Mammalian↗