Folia Biologica
Journal of Cellular and Molecular Biology, Charles University 

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Fol. Biol. 2002, 48, 149-153

https://doi.org/10.14712/fb2002048040149

The Status of the Chromatin of Human Preimplantation Embryos with Good Morphology

Stefka M. Delimitreva

Human IVF Laboratory, Department of Biology, Medical Faculty, Sofia, Bulgaria

Received December 2001
Accepted March 2002

The data about the relation and succession of blastomere fragmentation, cleavage rate and chromatin anomalies in preimplantation mammalian embryos are empirical and controversial at present. In this work we studied the proportion of nuclear fragmentation and condensation in 3-5-cell stage human embryos with no or minimal blastomere fragmentation (morphological class A and B, respectively) and the possibilities to perform FISH chromosomal analyses with them. We observed different stages of chromatin damage in blastomere nuclei corresponding to the steps of nuclear apoptotic changes well known in many cell types. The ploidity analysis of chromosomes 1,5,19 and X was determined as successful in embryos which had at least 2 out of 3, 3 out of 4 or 3 out of 5 normal nuclei with an equal number of FISH signals. There was no difference in the percentage of abnormal nuclei among the A- and B-class embryos. Tendencies noted by us suggest that the minimal blastomere fragmentation (up to 20% of perivitelline space) does not preclude the normal nuclear status allowing successful ploidy testing. The presence of condensed chromatin is a critical factor for interphase cytogenetic analysis of single early blastomeres.

References

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