The developmental potential of mouse 16-cell blastomeres

Area of Science:

• Developmental Biology
• Embryology
• Cell Biology

Background:

• Mouse morulae at the 16-cell stage consist of distinct outer and inner blastomere populations.
• These subpopulations differ in size and cell surface polarization, suggesting potential functional divergence.

Purpose of the Study:

• To investigate the developmental potential of isolated outer and inner blastomere subpopulations from mouse morulae.
• To assess the capacity of these subpopulations to form blastocysts and support postimplantation development in vitro and in vivo.

Main Methods:

• Isolation of outer (larger, polar) and inner (smaller, apolar) blastomeres from mouse 16-cell morulae.
• Reaggregation of 16-cell aggregates using outer, inner, or mixed cell populations.
• In vitro assessment of blastocyst formation, including trophectoderm and inner cell mass development.
• In vivo assessment of postimplantation development following transfer to pseudopregnant recipients.

Main Results:

• All aggregates (outer, inner, mixed) formed blastocysts in vitro, containing trophectoderm and alkaline phosphatase-positive inner cell masses.
• Outer cell aggregates showed slower compaction but earlier fluid accumulation and more cells at the blastocyst stage compared to inner cell aggregates.
• Blastocysts derived from both outer and inner cell aggregates supported normal postimplantation development in vivo.

Conclusions:

• Both outer and inner blastomere subpopulations possess totipotency, capable of forming complete blastocysts and contributing to normal embryonic development.
• Differences in cell properties correlate with distinct developmental timing during blastocyst formation.
• The study highlights the plasticity and developmental potential of early embryonic cell lineages in mice.