Follicular survival, activation of primordial follicles and DNA fragmentation after storage of goat ovaries at 35ºC in supplemented Minimal Essential Medium

Résumé

This study evaluated the effect of caprine ovarian tissue transportation conditions (medium supplementation and transportation duration) on the morphology, DNA fragmentation and development of cultured and non-cultured preantral follicles. After the fragmentation of ovaries, one fragment was fixed (fresh control) while the remaining slices were placed individually in two different conservation media (Minimal Essential Medium - MEM without supplementation or supplemented MEM, i.e. MEM+) and stored at 35ºC for 6 or 12 h without (non-cultured) or with a subsequent 5-day in vitro culture in supplemented α-MEM. After transportation, followed or not by in vitro culture, the fragments were processed for histological and Terminal deoxynucleotidyl transferase (TdT) mediated dUTP nick-end labeling (TUNEL) examination. For the preserved and non-cultured fragments, the percentages of normal follicles after the storage of ovarian tissue in MEM+ for 6 h and the DNA fragmentation rates after preservation in MEM for 6 h and MEM+ for 6 or 12 h were maintained similar to the fresh control. However, all cultured treatments reduced the proportion of normal follicles and increased the percentage of TUNEL-positive cells as compared to the fresh control and non-cultured treatments. On the contrary, all culture conditions (except after preservation in MEM for 6 h) promoted an increase in primordial follicle activation. In conclusion, the use of an enriched medium (MEM+) during ovary transportation is preferable to maintain satisfactory rates of normal follicles after the preservation of caprine ovarian tissue at 35ºC for up to 6 h, without affecting the ability of the primordial follicle to grow in vitro.