Elsevier

Developmental Biology

Volume 167, Issue 1, January 1995, Pages 213-226
Developmental Biology

Full Papers
Restricted Distribution of Tetraploid Cells in Mouse Tetraploid ↔ Diploid Chimaeras

https://doi.org/10.1006/dbio.1995.1018Get rights and content
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Abstract

Tetraploid mouse embryos were produced by electrofusion at the 2-cell stage, cultured overnight, and aggregated with normal diploid embryos to produce tetraploid↔diploid (4n ↔ 2n) chimaeric conceptuses. At 712 days the 4n ↔ 2n chimaeras were usually smaller and developmentally retarded compared to control diploid↔diploid chimaeras. At 12 1/2 days the 4n ↔ 2n chimaeras had heavier placentas but there was no significant difference in fetal size. Tetraploid cells showed a restricted tissue distribution at both developmental stages studied: 4n cells were commonly present in both the primitive endoderm and the trophectoderm lineages but they rarely contributed to the primitive ectoderm lineage. The overall similarity in the distribution of tetraploid cells at 712 and 1212 days implies that whatever causes the restricted tissue distribution operates largely before 712 days. There was no evidence for excessive embryonic losses of 4n ↔ 2n chimaeras. So, if the restricted distribution of 4n cells was a result of cell selection, the mechanism is more likely to involve loss of 4n cells from the primitive ectoderm early in development rather than selective death of conceptuses with tetraploid cells in this lineage. Alternatively, 4n cells may be preferentially allocated to the trophectoderm and primitive endoderm rather than the primitive ectoderm layer at the blastocyst stage.

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