ABSTRACT
OBJECTIVE: To examine the chromosomal content of embryos resulting from metaphase I (MI) oocytes obtained after ovarian hyperstimulation for IVF. DESIGN: Prospective cohort study. SETTING: University-based IVF Center, Assaf Harofeh Medical Center, Tel Aviv University, Israel. PATIENT(S): One hundred fifty women undergoing assisted reproduction technique (ART). INTERVENTION(S): Intracytoplasmic sperm injection (ICSI) was performed in MI oocytes that were retrieved after ovarian stimulation. A portion of these oocytes extruded their polar body (rescued in vitro-matured metaphase II [IVM-MII]) after different incubation periods and the remainder did not (arrested MI oocytes). Fluorescence in situ hybridization was performed using probes for chromosomes X, Y, 18. MAIN OUTCOME MEASURE(S): Fertilization rate, number of blastomeres, and embryo euploidy. RESULT(S): Embryos from rescued IVM-MII oocytes showed significantly higher fertilization rates and more blastomeres per embryo compared with those from arrested MI oocytes (58.5% vs. 43.9% and 5.7 vs. 5.0, respectively). The chromosomal analysis of these embryos revealed a high rate of aberrations (80.6%), mainly complex mosaics. This rate was elevated in embryos from arrested IVM oocytes (97.2%), and after longer incubation periods. No chromosomally normal embryos were found after 24 hours of incubation of their corresponding oocytes. CONCLUSION(S): Embryos originating from MI oocytes have a high rate of chromosomal aneuploidy, and their replacement should be reconsidered.
Subject(s)
Embryo, Mammalian/cytology , Embryo, Mammalian/metabolism , Metaphase , Oocytes/physiology , Ovulation Induction , Aneuploidy , Cells, Cultured , Chromosome Aberrations/embryology , Chromosome Aberrations/statistics & numerical data , Cleavage Stage, Ovum/cytology , Cleavage Stage, Ovum/physiology , Cytogenetic Analysis , Female , Fertilization/physiology , Humans , Male , Metaphase/genetics , Metaphase/physiology , Oocyte Retrieval/methods , Oocytes/cytology , Oocytes/metabolism , Oogenesis/genetics , Sperm Injections, Intracytoplasmic , Time FactorsABSTRACT
The ortho ester Claisen rearrangement of trisubstituted allylic alcohols exhibits significant levels of diastereoselection. In E allylic alcohols, a 1,3-diaxial interaction develops in the chairlike transition state leading to the anti isomer, rendering the reaction syn selective by a factor of 3-5 to 1. In Z allylic alcohols, the 1,3-diaxial interaction develops in the transition state leading to the syn isomer, generating an anti:syn selectivity of 6-15 to 1. The relative stereochemistry of the syn isomer was confirmed independently by the synthesis of the mycotoxin botryodiplodin.
