**5. Our experiences with cryopreservation of gametes, embryos and tissues**

We have cryopreserved sperm since 1991, and we introduced embryo freezing in 1995. In the beginning, we performed slow freezing by Planer, but from 2007, we prefer vitrification. Well‐ functioning cryopreservation was an essential prerequisite for a donation of gametes and embryos program. Within the centres of assisted reproduction, we had the first and the largest sperm bank in the Czech Republic from 1995 (currently, we have 100 donors).

We have also built a centre for fertility preservation for both male and female oncologic patients. Methods of preserving the fertility in young women can be divided into three cryopreservative methods: embryo‐, mature oocyte‐ and ovarian tissue‐cryopreservations. We have started as the first with ovarian tissue freezing and sperm freezing before gonadotoxic treatment in the Czech Republic. We cryopreserved ovarian tissue of 23 women before gonadotoxic treatment (from January 2006 to December 2015). During October 1995 to December 2015, we cryopreserved the sperm of 1231 men—oncologic patients (587—testicular cancer diagnosis). The testicular cancer survivors have a good chance of fathering a child by using sperm cryopreserved prior to the oncology treatment, even when it contains only limited number of spermatozoa. There are 41 patients in our centre, who returned for infertility treatment underwent 58 treatment cycles with cryopreserved sperm. Totally, 20 pregnancies were achieved, that is 34.5% pregnancy rate. The implementation of all young oncological patient sperm cryopreservation has an important place in our laboratory methods.
