Cryopreservation and short-term culture of isolated caprine primordial follicles

Cryopreservation of primordial follicles in ovarian tissue has been extensively described in several species. However, until now no information is available concerning cryopreservation of isolated caprine primordial follicles. The aim of this work was to assess the toxicity of dimethylsulphoxide (DMSO) and propanediol (PROH), in different concentrations (1.5 and 3 M), on isolated caprine primordial follicles and verify the viability of these follicles after freezing/thawing procedures. Follicular viability was tested by trypan blue staining before and after 24 h of in vitro culture. Before culture the percentage of viable primordial follicles after the toxicity test and cryopreservation were similar to fresh follicles (control). On the other hand, after 24 h of in vitro culture the percentage of viable follicles cryopreserved in 1.5 M DMSO or PROH was significantly inferior than non-cryopreserved follicles, exposed or not to cryoprotectants. In conclusion, this study showed that isolated primordial follicles can be successfully cryopreserved in 1.5 DMSO or PROH, resulting in more than 60% viable follicles after a short-term culture. It is also concluded that in vitro culture is an essential parameter for the evaluation of follicular viability after cryopreservation.