In the development of culture systems for primordial follicles is important for studying their growth and differentiation in vitro. In this study, we investigated the effect of minimal essential medium (MEM), coconut water solution (CWS), and MEM supplemented with CWS on the morphology and activation of primordial goat follicles. Ovarian, cortical tissue pieces were cultured for 1 or 5 days in MEM, CWS, or MEM supplemented with 5, 10, 20, 50, 80, 90, or 95% CWS. Both MEM and CWS were supplemented with BSA, ITS, glutamine, pyruvate, and hypoxanthine. On day 0 and after 1 or 5 days of in vitro culture, the cortical pieces were fixed for histological evaluation. Based on their morphology, follicles were classified as primordial, developing and intact, or atretic. Follicular diameter was evaluated before and after culture. Mitotic activity of granulosa cells was studied by immunolocalization of proliferation cell nuclear antigen (PCNA). The results showed that the percentage of primordial follicles was reduced (P < 0.05) and was concomitant with the increase of the percentage of developing follicles in all media tested after 5 days culture. The highest rate of primordial follicle activation was observed after 5 days of culture when ovarian pieces had been cultured in MEM or MEM supplemented with 5 or 10% CWS. However, culturing follicles for 5 days in a mixture of MEM and 20% or higher percentages of CWS reduced their activation and viability. In all media tested, mean follicular diameters had significantly increased after 5 days of culture when compared to those measured at day 0 and day 1. Immunohistochemical analysis showed that primordial follicles generally do not stain for PCNA both in noncultured and cultured tissues, whereas the granulosa cells of developing follicles do express PCNA after culture. In conclusion, goat primordial follicles were activated and kept viable after in vitro culture in MEM or in a mixture of MEM with low proportions (10% or less) of CWS. Compared to MEM alone, addition of CWS to MEM, does not improve the survival, activation, or further development of the primordial follicle population during culturing of goat ovarian cortical pieces.