Santiago Brugo Olmedo M.D.
Medical Director
Seremas Medicine for men and women
Seremas Home Seremas Procedures Seremas Cryopreservation Program Seremas Oocytes / Ovarian Tissue Cryopreservation

Oocytes / Ovarian Tissue Cryopreservation

Ovarian tissue and oocytes cryopreservation is a methodology not broadly offered nowadays, and only to a particular group of women since its use is still restricted because of being an experimental technique, whose results after thawing offer a number of questions and much reduced survival rates, especially because of methodological problems.

Inconvenience for the case of ovarian tissue cryopreservation, as we are dealing with a “group” of different types of cells, is that they have by nature characteristics and requirements of particular and specific cryoprotectives. This means that later on, when thawing the tissue, recovering the different cells is not as successful as expected. Besides, the other inconvenience which arises is that “this cryopreserved tissue”, so that it can be later used by the patient, will have to be thawed and re-implanted in some part of the patient’s body so that it can develop again and originate, under proper conditions, the development of follicles which will give origin to oocytes. This is still subject of research and scientific journals worldwide since scientists have not yet found the ideal “protocol” to use cryopreservation-thawing and transplant of ovarian tissue as a routine.

In the case of oocytes in stage Metaphase II (this means mature) there is also controversy since the “greatest weakness” of this stage is that its chromosomic components are not protected inside the oocyte instead of being kept safe inside the nuclear structure like the case of oocytes in stage Prophase I (immature). That is the reason why when cryopreserving them, cryoprotectives agents alter in some way the situation of chromosomes and therefore these oocytes would show a slight increase in chromosomic alterations of thawed oocytes. Besides, survival after thawing is relatively low due to the fact that this oocyte is highly vulnerable to the cryoprotectives agents. Nevertheless, many protocols have been proved and this one seems to be the best option in the case we need to preserve feminine fertility, as shown in published works regarding it. The question would be why not to cryopreserve immature oocytes and the answer is that up to the moment, we have not been able to develop protocols, in human beings, regarding “In Vitro maturation” of these oocytes in such a way that we can get, cryopreserve, thaw, mature them In Vitro, get Metaphase II oocytes able to fertilize and give origin to healthy embryos which can result in evolutive pregnancies.

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