Surface changes of the rat embryo before implantation

Area of Science:

• Reproductive biology and developmental science.

Background:

• The preimplantation embryo undergoes significant morphological changes.
• The zona pellucida, a protective layer, obscures the dynamic surface of the early embryo.

Purpose of the Study:

• To investigate the dynamic changes in the rat zygote surface during the preimplantation period.
• To characterize the ultrastructure of the rat embryo surface after zona pellucida removal.

Main Methods:

• Scanning electron microscopy (SEM) was used to examine the rat embryo surface.
• The zona pellucida was dissolved using brief adenosine triphosphate (ATP) treatment.
• Embryos were analyzed at various preimplantation stages (1 to 4.5 days).

Main Results:

• The zona pellucida presents a static, perforated network structure.
• Post-zona dissolution, the zygotic surface exhibits daily morphological changes.
• Microvilli number and length increase with developmental progression.
• Early blastocysts display heterogeneous microvilli and polar membranous ruffles.

Conclusions:

• The rat zygote surface undergoes dynamic remodeling during preimplantation development.
• Surface modifications, including microvilli and ruffles, may support changing metabolic needs and trophoblast invasion.