Developmental capacity is unevenly distributed among single blastomeres of 2-cell and 4-cell stage mouse embryos

Katarzyna Krawczyk,Marek Maleszewski,Ewa Kosyl,Karolina Częścik-Łysyszyn,Tomasz Wyszomirski

doi:10.1038/s41598-021-00834-1

Abstract

During preimplantation development, mammalian embryo cells (blastomeres) cleave, gradually losing their potencies and differentiating into three primary cell lineages: epiblast (EPI), trophectoderm (TE), and primitive endoderm (PE). The exact moment at which cells begin to vary in their potency for multilineage differentiation still remains unknown. We sought to answer the question of whether single cells isolated from 2- and 4-cell embryos differ in their ability to generate the progenitors and cells of blastocyst lineages. We revealed that twins were often able to develop into blastocysts containing inner cell masses (ICMs) with PE and EPI cells. Despite their capacity to create a blastocyst, the twins differed in their ability to produce EPI, PE, and TE cell lineages. In contrast, quadruplets rarely formed normal blastocysts, but instead developed into blastocysts with ICMs composed of only one cell lineage or completely devoid of an ICM altogether. We also showed that quadruplets have unequal capacities to differentiate into TE, PE, and EPI lineages. These findings could explain the difficulty of creating monozygotic twins and quadruplets from 2- and 4-cell stage mouse embryos.

Highlights

During preimplantation development, mammalian embryo cells cleave, gradually losing their potencies and differentiating into three primary cell lineages: epiblast (EPI), trophectoderm (TE), and primitive endoderm (PE)
We aimed to examine whether single cells isolated from 2- and 4-cell embryos differ in their ability to generate the progenitors and cells of blastocyst lineages (TE, EPI, and PE)
Our results demonstrate that the dissimilarities in the number and proportion of cells of individual cell lineages between monozygotic twin blastocysts and controls deepen over the course of development and are more pronounced at the late blastocyst stage

Summary

Introduction

Mammalian embryo cells (blastomeres) cleave, gradually losing their potencies and differentiating into three primary cell lineages: epiblast (EPI), trophectoderm (TE), and primitive endoderm (PE). Cells with elevated Cdx[2] levels tend to become the future TE, while those with minimal Cdx[2] expression contribute preferentially to the ICM Another factor that can serve as a predictive measure of future lineage segregations in the early mouse embryo is the differential kinetic behaviors of specific transcription factors. Cells with faster kinetics of these factors, manifested by lower nuclear retention rates and decreased accessibility to DNA binding sites, contribute mostly to the TE These results together suggest that cells as early as at the 2- and 4-cell stages can already exhibit differences in fate-determining gene expression patterns and in the activity of specific cell-fate regulators, leading to unequal developmental fate and potential

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