THE FIRST PGD TYPE. A BIOPSY OF POLAR BODIES

The first stage of PGD is a biopsy of cellular material that can be performed on various stages of embryo development.
A biopsy of the 1^st polar body is carried out on the day of follicular puncture (day 0).

In 16 hours after insemination, a biopsy of the 2^nd polar body is carried out. A biopsy of the 1^st and a biopsy of the 2^nd polar body are performed separately for PCR analysis.

For FISH, biopsies of the 1^st and the 2^nd polar bodies can be carried out immediately after insemination, i.e. in the morning of the day following follicular puncture.

Polar bodies allow only the analysis of chromosomal disorders of the maternal genome and the analysis of meiosis I and II errors. This method can be combined with a biopsy of a blastomere on day 3 of the development.

The advantages of the method are:

• Enough time for genetic diagnosis;
  
• An embryo transfer in the same cycle;
  
• A minimal risk of embryo damage;
  
• can be conducted in countries where embryo diagnosis is prohibited (Germany, Austria).
  
  

The limitations of the method are:

• It reflects neither post-zygotic aneuploidies nor paternal aneuploidies;
  
• It cannot determine an embryo's gender;
  
• A PB biopsy cannot be repeated;
  
• Consecutive biopsies of the 1^st PB in 4 hours after follicular aspiration and of the 2^nd PB in 16-18 hours after insemination are strenuous and induce stress in an oocyte/zygote;
  
• A high price for genetic diagnosis (10 oocytes = 20 samples).