Visualization of second polar body chromosomes in fertilized and artificially activated mouse oocytes treated with okadaic acid.
OBJECTIVE
Our objective was to develop a new reliable method for cytogenetic analysis of the chromosome set in second polar bodies (PBs) from one-cell-stage mouse embryos.


METHODS
The study took place at the Reproductive Biology and Experimental Cytogenetics Laboratories.


METHODS
Oocytes from F1 hybrid and T6/T6 mice were fertilized in vitro and artificially activated with ethanol. Zygotes, parthenogenetic embryos, and isolated second PBs were treated with 10 microM okadaic acid (OA) for 1-2 hr, further cultured in plain medium, and fixed. Chromosomal preparations were made and C-banded, and the number of chromosomes in second PBs and embryos was counted.


RESULTS
OA-induced nuclear envelope breakdown in pronuclei as well as in second PB nuclei. Countable chromosome plates were obtained in 92-93% of second PBs treated 4-4.5 hr after activation. The T6 marker chromosome could easily be recognized in second PBs from T6/T6 mice. A haploid set of chromosomes was obtained in 18 of 19 isolated second PBs treated with OA 4-5 hr after activation.


CONCLUSIONS
Treatment of second PBs with OA allows visualization of the PB chromosomes. Cytogenetic analysis of the second PB and the corresponding oocyte constitutes a new approach for the study of meiotic nondisjunction in experimental cytogenetics. The chromosomal study of isolated second PBs seems to be promising for clinical preimplantation cytogenetics.
Dyban
A P
AP
Reproductive Genetics Institute, Illinois Masonic Medical Center, Chicago 60657.
De Sutter
P
P
Dozortsev
D
D
Verlinsky
Y
Y
D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects; D002875:Chromosomes / Q000648:ultrastructure*; D004988:Ethers, Cyclic / Q000494:pharmacology*; D005260:Female; D005307:Fertilization in Vitro; D006238:Haploidy; D007399:Interphase / Q000187:drug effects; D008540:Meiosis / Q000187:drug effects*; D051379:Mice; D008810:Mice, Inbred C57BL / Q000196:embryology; D008811:Mice, Inbred DBA / Q000196:embryology; D019319:Okadaic Acid; D009865:Oocytes / Q000187:drug effects / Q000648:ultrastructure*; D010312:Parthenogenesis / Q000187:drug effects*; D015053:Zygote / Q000187:drug effects / Q000648:ultrastructure*
D004988:Ethers, Cyclic; D019319:Okadaic Acid