The effect of bpV(HOpic) on in vitro activation of primordial follicles in cultured swine ovarian cortical strips.

The vanadate-derivative dipotassium bisperoxo (5-hydroxy-pyridine-2-carboxylic) oxovanadate (V) (bpV(HOpic)), a pharmacological inhibitor of phosphatase and tensin homolog (PTEN), has been used in ovarian follicle culture systems for activation of follicular growth in vitro and suggested to be responsible for primordial follicle survival through indirect Akt activation. For pig ovarian tissue, it is still not clear which culture medium needs to be used, as well as which factors and hormones could influence follicular development; this also applies to bpV(HOpic) exposure. Therefore, ovarian cortical strips from pigs were cultured in 1 µM bpV(HOpic) (N = 24) or control medium (N = 24) for 48 hr. Media were then replaced with control medium and all tissue pieces incubated for additional 4 days. The strips were embedded in paraffin for histological determination of follicle proportions at the end of the culture period and compared to histological sections from tissue pieces without cultivation, which had been embedded right after preparation; comparison of healthy follicles for each developmental stage was performed to quantify follicle survival and activation. After 6-day culture, follicle activation occurred in tissue samples from both cultured groups but significantly more follicles showed progression of follicular development in the presence of 1 µM bpV(HOpic). The amount of non-vital follicles was not significantly increased during cultivation. BpV(HOpic) affects pig ovarian follicle development by promoting the initiation of follicle growth and development, similar as in rodent species and humans.