Cryopreservation

Apr 15, 2012 , Michaela Knollová

ket-kryokonzervace.jpg - kopie
ket-kryokonzervace.jpg - kopie
Cryopreservation is a method in which are eggs, sperms and also embryos preserved. All samples are carefully tested for diseases such as HIV or jaundice before cryopreservation and afterwards frozen to -195 °C. The freezing process can be done by either gradual lowering of the temperature or by direct freezing. However, the drain off of samples is necessary before performance of each method. Efficiency of the cryopreserved samples is relatively low, at around 18%, but it is not yet known why it is so.

Cryopreservation

Cryopreservation is a method in which are eggs, sperms but also whole embryos preserved by deep freeze for future use. Samples that are intended to be frozen are carefully tested in the quality, and for infectious diseases such as HIV and hepatitis B and C. This method is performed by laboratories in centres of assisted reproduction. The way in which will be tissue frozen depends on its type and stage of its development.

Development of eggs and sperms

Development of human sex cells is complex process. Male sex cells are formed in process of spermatogenesis and female eggs are created during the oogenesis. Male sex cells, i.e. sperms, are formed by fission of germ cells which are located in the walls of the convoluted seminiferous tubules. Female sex cells, the eggs, are formed in the ovaries. The origin and development of gametes in men and women is controlled by sex hormones. The follicle stimulating hormone (FSH) and luteinizing hormone (LH) undertake a leading function of this developmental process. Besides them, there are also other hormones produced in the gonads. Oestrogen is produced by the ovaries and testosterone is created in the testes. Germ cells are being divided during their development. The division continues until each cell contains only half of its genetic information. If it comes to fertilization of the egg by sperm in the fallopian tube, the both halves of genetic information will merge and create the embryo.

Indications of cryopreservation

Donated sperms and as well as sperms taken from men who will undergo cytostatic treatment in which might be spermatogenesis impaired can be used for cryopreservation, or sperms which are collected with demanding surgical method from testicle that the new harvest does no not has to be repeated. With regard to the embryos, embryos from donated eggs and extra embryos created in in vitro fertilization (IVF) in which are taken eggs fertilized by collected sperms can be used to cryopreservation. If  there are more fertilized eggs or embryos than it is needed for the transfer to uterus, it is possible to preserve them with Cryopreservation for repeated use.

Process of cryopreservation

Basically, two cryopreservation methods are normally used, i.e. rapid freezing and slow freezing of tissue. During the process of slow freezing, the sample are inserted into the device that gradually reduces its temperature to about -195 °C over several hours. However, the freezing process is not so simple. If there are any water particles left after the freezing process, ice crystals which would destroy the tissue will be formed. Therefore, special substances which drain off the sample are used, for example, propylene glycol. Afterwards, the frozen samples are stored at the temperature of -195 °C which is maintained by cooling with liquid nitrogen. Tissues can be stored for 5 years but on request of infertile couple can be their embryos kept even longer.

Defrosting in cryopreservation

If we want to use cryopreserved samples again, it is necessary to let them thaw. Preservative solutions are gradually washed out from them during defrosting process. Afterwards, it is necessary to determine how severely was sample damaged by deep freeze. The eggs tolerate cryopreservation the worst. Only about 18% of the eggs is suitable for further use after defrosting process. Cryopreservation of sperms and the embryos is far more successful. About 85% of the embryos is successfully cryopreserved. But the question is whether cryopreservation reduces the likelihood of conception or not. Scientists assume that this method has no influence on the probability of success in conception by this way of fertilization. It is true that the number of successfully nidated embryos which were cryopreserved is lower than that of newly developed. This can be explained so that for the cryopreservation are used only embryos of lower quality because the best ones are normally given to patient immediately. For future, it is discussed about possible cryopreservation of ovarian tissue and testes.

Application of cryopreserved sperms and embryos

It is possible to introduce cryopreserved sperms into cervix uteri after the defrosting process. However, we use mainly one of the assisted reproduction techniques. That one is intrauterine insemination (IUI) in which are sperms injected directly into the woman's uterus. Accordingly, the path which must sperms pass to reach the eggs is shortened and the chances of fertilization are greatly increased. Intracytoplasmic sperm injection (ICSI) can be used as alternative method in case of low number and quality of sperms. Sperm of the most quality is carefully selected under a microscope and afterwards injected to the egg which was collected in advance.

Conception difficulties

Developmental disorders related to sex cells are nowadays more and more common. In women, the problem is in the formation and maturation of eggs or in obstructed fallopian tubes. In men, the amount of sperms and their quality is deteriorated. This both unpleasant situations can be caused by hormonal disorders, overcome infectious diseases, previous chemotherapy or radiotherapy and other underlying diseases. If the couple can not conceive naturally within two years, it is advisable to see a doctor and start thinking about methods of assisted reproduction.

Diskuze:

Pesemoips: popular pills online compra cialis italy http://zithazi.com - buy Azithromycin cialis discount coupon
where to buy viagra in la http://kaletra24.com - kaletra generic when does cialis go generic
buy viagra cialis uk http://alexa24ph.com - buy sildenafil order viagra canadian pharmacy

April 7, 2020 7:47 AM

Pesemoips: buy levitra qatar http://zithazi.com - zithromax cheapest cialis internet
viagra for sale http://tadal24ph.com - cialis coupon cheap viagra au
can buy cialis uk http://hydroxychloroquine24.com - plaquenil online levitra cheap canada

April 6, 2020 9:17 PM

Pesemoips: where can i buy cialis in london http://kaletra24.com - kaletra cialis sale philippines
cialis generique discount http://alexa24ph.com - viagra buy cialis professional 20 mg
buy levitra thailand http://aralenph.com - chloroquine viagra sale vegas

April 6, 2020 10:24 AM

Pesemoips: buy real viagra online http://tadal24ph.com - cialis cost viagra sale dc
cialis coupon http://zithazi.com - zithromax buy genuine cialis online
buy generic viagra online overnight http://aralenph.com - buy alaren generic can you buy real viagra online

April 5, 2020 11:05 PM

Pesemoips: buy cialis with mastercard http://hydroxychloroquine24.com - generic plaquenil buy generic cialis europe
buy viagra hcmc http://alexa24ph.com - viagra without a doctor prescription walmart is there a generic cialis available?
cheap viagra cialis levitra http://aralenph.com - buy alaren generic viagra without a doctor prescription

April 5, 2020 11:44 AM

Pesemoips: buy cialis beijing http://zithazi.com - zithromax buy real viagra cheap
prices of cialis http://tadal24ph.com - cialis cost canada levitra buy online
how to buy cialis from canada http://alexa24ph.com - viagra coupons from pfizer buy viagra profile

April 5, 2020 12:28 AM

Pesemoips: where to buy levitra online no prescription http://hydroxychloroquine24.com - buy plaquenil kamagra cheap viagra
very cheap generic viagra http://zithazi.com - cheap zithromax cialis soft tablets
buy viagra no prescription canada http://tadal24ph.com - cheap cialis order cialis/viagra online

April 4, 2020 1:11 PM

Pesemoips: buy viagra http://alexa24ph.com - cheap viagra buy viagra legal
order viagra with paypal http://tadal24ph.com - cialis cost cialis 20 mg price
buy cialis at boots http://hydroxychloroquine24.com - buy hydroxychloroquine online buy cialis online germany

April 3, 2020 2:41 PM

Pesemoips: generic levitra cheap http://aralenph.com - buy chloroquine online how to buy levitra
buying cheapest generic cialis soft tab http://alexa24ph.com - generic viagra 100mg buy levitra canada online
order cialis india http://hydroxychloroquine24.com - buy plaquenil how to buy viagra or cialis

April 3, 2020 4:23 AM

Pesemoips: cialis online best place buy http://alexa24ph.com - viagra without a doctor prescription buy cialis vegas
daily cialis pills http://aralenph.com - chloroquine can you buy viagra in dubai
order viagra in canada http://tadal24ph.com - cialis online generic mail order viagra

April 2, 2020 3:49 PM

Pesemoips: buying cialis online in canada http://tadal24ph.com - buy cialis order viagra men
order viagra by phone http://alexa24ph.com - viagra without doctor prescription cheap levitra in uk
order viagra plus http://zithazi.com - zithromax price fake cialis pills

March 31, 2020 2:02 AM

Pesemoips: viagra 100 mg buy http://alexa24ph.com - sildenafil buy cialis and viagra
buy viagra australia online http://aralenph.com - alaren online cialis pills picture
viagra cialis http://tadal24ph.com - generic cialis viagra buy philippines

March 30, 2020 1:44 PM

Pesemoips: cheap viagra men http://alexa24ph.com - generic viagra cheapest cialis in canada
buy cialis with paypal http://hydroxychloroquine24.com - hydroxychloroquine 200 mg price in india can you buy cialis over counter usa
viagra prices http://kaletra24.com - kaletra how to buy viagra online in the uk

March 30, 2020 2:32 AM

WalterCaf: viagra over the counter walmart http://hydroxychloroquine24.com - buy plaquenil cheap quick viagra
buy cialis in europe http://kaletra24.com - kaletra price ordering cialis online legal
buy viagra where http://zithazi.com - Azithromycin online cialis viagra levitra sale

March 28, 2020 11:35 PM

Vateasex: viagra buy online ireland http://alexa24ph.com - viagra buy viagra cialis or levitra

March 28, 2020 6:33 PM

Pesemoips: cheap viagra uk sale http://alexa24ph.com - viagra online cheap viagra au
order brand name cialis http://kaletra24.com - kaletra generic where to buy viagra in london
red viagra tablets http://hydroxychloroquine24.com - buy plaquenil how to buy cialis in toronto

March 28, 2020 2:12 PM

JapSpeelm: cheap viagra for sale http://hydroxychloroquine24.com - hydroxychloroquine viagra cheap thailand
where to order viagra http://zithazi.com - Azithromycin online order brand name viagra online
buy viagra now online http://tadal24ph.com - buy cialis buy generic cialis canada

March 28, 2020 12:57 PM

GeorgePeack: when does cialis go generic http://aralenph.com - alaren price order cialis with paypal

March 28, 2020 11:02 AM

Pesemoips: buy viagra online england http://tadal24ph.com - cialis site es cheap viagra
buy cialis online europe http://alexa24ph.com - generic viagra buy online levitra usa
buy authentic cialis http://zithazi.com - cheap zithromax best online pharmacy to buy cialis

March 28, 2020 7:58 AM

JeremyDiupe: viagra buy with paypal http://aralenph.com - buy alaren what color are cialis pills
buy female viagra http://tadal24ph.com - how much does cialis cost at walmart viagra sale united states
how can i buy viagra http://kaletra24.com - cheap kaletra buy cialis with prescription

March 28, 2020 5:33 AM

1 2 3 4 5 6 7 8 9 10 Next page

Post a Reply

Dear readers, we value your opinion. We want you to feel comfortable here, therefore we monitor all discussions and delete posts that are in conflict with our rules and regulations.




E-mail