Effect of assisted hatching by partial zona pellucida dissection on mouse embryos in vitro

Area of Science:

• Reproductive Biology
• Developmental Biology
• Assisted Reproductive Technology

Background:

• The zona pellucida is a crucial outer layer protecting mammalian embryos.
• Assisted hatching techniques are explored to improve in vitro fertilization (IVF) success rates.
• Partial zona dissection (PZD) is a method to aid embryo hatching.

Purpose of the Study:

• To investigate the impact of partial zona dissection (PZD) at the four-cell stage on mouse embryonic development.
• To evaluate the effect of PZD on the in vitro hatching process of mouse embryos.
• To determine if PZD influences the timing and success of embryo hatching.

Main Methods:

• Mouse embryos at the four-cell stage were subjected to partial zona dissection (PZD) using micropipettes.
• A small gap (one-sixth of the zona circumference) was created to minimize blastomere damage.
• PZD and control embryos were cultured in vitro under identical conditions and hatching rates were monitored daily.

Main Results:

• Partial zona dissection (PZD) significantly increased the percentage of embryos that initiated and completed hatching compared to controls.
• Hatching rates on day 4 were 44.1% for PZD embryos versus 22.0% for controls.
• Complete hatching rates on day 6 were 37.0% for PZD embryos and 26.8% for controls, indicating enhanced hatching.

Conclusions:

• Partial zona dissection (PZD) does not appear to be detrimental to mouse embryonic development in vitro.
• Creating an opening in the zona pellucida facilitates the hatching process.
• Further research is needed to ascertain if the enhanced hatching ability from PZD improves in vivo implantation rates.