Oocyte vitrification or cryopreservation on of the key point for successful donor egg banking. Already several companies build protocols for vitrification and warming( thawing) of oocyte process. Most of the IVF clinics and egg banks are using strictly these protocols.
But we need to consider that, a good vitrification and warming (thawing) process need also experience and theoretical knowledge of embryologist or laboratory technician. Oocyte is more sensitive than embryos during cryopreservation process. During the equilibration and vitrification of oocytes, timing and amount of media which is doing cell protection for the oocyte. But during warming (thawing) timing and micromanipulation of embryologist much more important for the quality of survival rate. Also every IVF laboratory has its own way to optimized vitrification protocol for better survival rate.
3 important points, which affect the quality of vitrification process:
- ice formation;
- balance of media composition;
- timing of micromanipulation.
Mostly under the stereo microscope embryologist follow the oocyte depending of time and according timing they load them to cryo device. Scientific team of Ovogene Egg Bank is using technology in this step. We are using a time lapse technology during vitrification and we decide according cytoplasmic composition when we need to load vitrify oocyte to cryo device. This is the one of key point how we increase our survival rate for oocyte vitrification and warming( thawing).
If we are talking about survival rate than we need to consider also morphological quality of donor oocyte as well. We know that, egg donors mostly have good number of follicles and when IVF specialist stimulate them they are able to give more number of oocytes than usual. Each follicle is growing under standards but still there are follicles on different sizes and qualities which give different morphological quality of oocytes. In this point embryologist need to make exact morphological assessment before vitrification process.
We prefer to use strict criteria for oocyte assessment. Our scientific team firstly analyze donor oocyte for cumulus complex quality. Some of the oocyte may have low quality, tick and bloody cumulus complex which may affect also other oocytes. We prefer to eliminate such oocytes for the denudation (cumulus cell complex cleaning) process. After the denudation process we make first morphological assessment under phase contrast microscope with morphological determination software.
Software may show us thickness of zona pellucida, cytoplasmic granulation and polar body quality as well. After the software we also check quality and real time place of meiotic spindle. This does not affect to quality of vitrification and thawing but meiotic spindle may effect directly quality of embryos and pregnancy outcome.
Finally, after these strict morphological assessments we are more than sure about quality and survival rate. Our team has up to 10 years of experience for donor egg banking, oocyte thawing and vitrification. We know well our responsibilities in front of our patients and customers. We are working more sensitive under our strict criteria and we are using technology with our experience together.