ART and Zona hatching how helpful is laser assisted Hatching of Zona?

 

Q. 1 To maximize the implantation rate , on which day , to transfer the embryo In IVF-ET programme? What is your opinion?  Day 2 or day 5 at blastocyst stage? Ans:- Blastocyst transfer is better as implantation rate  is high. Assisted zona hatching has been used in  vitro fertilization (IVF) programs for several years. We know that successful hatching of the embryo from the zona pellucida is a prerequisite for implantation in the uterus.

Assisted zona hatching came into limelight in IVF cycles to breach the zona pellucida and promote the natural process of hatching.  

 

Q. 2: What is the success rate of Zona drilling and blastocyst stage transfer? Ans: Though embryo transfer programs started off with day 2 transfer; success rates were then usually much lower (10%—20%) but  ,  IVF had a major breakthrough when its successful blastocyst culture dramatically increased the success rates to around 40%. Blastocyst transfer was not only more physiological but also the strongest of embryos which bypass the 4—8 cell block and survived blastocyst and hatching stages were transferred.

 Q,3: Why still implantation rate is so low?? Ans: Although human blastocyst expands readily in vitro, its blastocyst rate very heavily depends on laboratory environment, culture media, and techniques. Majority of blastocyst that have hatching problems are unable to completely hatch out of their zona pellucida and subsequently degenerate by day 6 or even day 7.

Q.4 : What is the role of Zona? The role of zona includes 1) initial binding of sperm, 2) induction of acrosome reaction, and 3) prevention of multiple sperm penetration and 4) prevention of of blastomere scatter with avoidance of direct contact with toxic by-products. It has been demonstrated that the zona is no longer essential for continuing of normal development in vitro, once compaction has been achieved.

 

 Q.5: What enzyme helps in vivo hatching?? Ans: It has been theorized that protease-like enzyme is released in vivo either by the blastocyst itself or by the endometrium which aids hatching and subsequent implantation. In view of the above-mentioned theory, assisted hatching was practiced by drilling small holes in the zona pellucida with acid Tyrode mechanically and more recently with laser (laser-assisted hatching [LAH]).