**5. Cryopreservation of genital tissues**

Freezing of ovarian tissue in humans relate primarily, but not only, to a dramatic measure to warrant availability of oocytes in cases of oncotherapy, when sterility is foreseen, similar to the ongoing sperm banking prior to onco- or hormonal therapy. Rescue of oocytes from frozen samples of ovarian cortex is then feasible for ART (Shaw & Trounson 2002). Both slow freezing and directional freezing had been assayed with acceptable results (Arav & Natan 2009), opening possibilities for the cryopreservation of large samples and even of whole ovary for autografting purposes and possibly evolving in oocyte banking as an insurance against childlessnes. Adult testicular samples (aspiration or biopsy) are mainly issued during biopsy for recovery of spermatids for ICSI (Keros et al 2005, Curaba et al 2011). However, the strongly ongoing research in adult stem cells shall be based on the absolute need of properly cryopreserving pre-pubertal testicular tissues. Transplantation of other organs or tissues (uterine in particular) is also within the scope of not-far, albeit discussable, scenarios (Bredkjaer & Grudzinskas 2001).

Regarding the porcine species, although there is no obvious rationale for most of the above considerations in human, it provides an excellent animal model for experimental reproductive medicine, particularly considering transplantation surgery. Porcine whole uteri were arterially perfused with CPA (DMSO) prior to slow controlled freezing. Rewarmed tissues were able to present live cells 7 h post rewarming (Dittrich et al 2006) and even to demonstrate contractility *in vitro* 60 min post-rewarming (Dittrich et al 2010). As such, comparative analyses of equilibrium freezing and vitrification procedures have involved pig ovarian fragments (Gandolfi et al 2006, Borges et al 2009), or whole ovaries (Imhof et al 2004). These attempts were all done using slow freezing, but evidence is now provided that vitrification of thin slices of ovarian cortex is feasible and that rewarmed primordial follicles from these samples were able to develop (albeit slower than controls) in murine xenografts (Moniruzzaman et al 2009). Further development in this area is expected.
