The present study aims to investigate the influence of two concentrations of ascorbic acid on the survival, growth , antral formation and m RNA expression of the matrix metalloproteinases - 9 (MMP - 9) and their tissue inhibitor - 2 (TIMP - 2) on caprine preantral follicles during long - term in vitroculture. Isolated preantral follicles were individ ually cultured without or with ascorbic acid at 50 μ g/ml (AA50) or 100 μ g/ml (AA100) during 18 days. The parameters evaluated were follicular viability, growth, antrum formation and extruded oocytes. The genesMMP - 9 and TIMP - 2 were quantified by real - timepolymer ase chain reaction (qPCR) after 18 days of culture in the control medium (MEM + ) or ascorbic acid (50 or 100 μ g/ml) and in fresh control (non cultured) . At the end of culture, AA50 significantly increased the percentage of viable follicles compared w ith other treatments . Moreover, mean daily increase in follicular diameter (μm/day) was significantly higher in the presence of both concentrations of ascorbic acid than in MEM + alone. Higher rates of antral formation and lower percentages of extruded oocy tes were observed in medium containing AA50 compared with control medium. Real Time RT - PCR assays showed that AA50 increase s MMP - 9 expression significantly compared with fresh control and MEM + alone. In conclusion, ascorbic acid at 50 μ g/ml was very import ant for the maintenance of caprine preantral follicle viability and development after in vitroculture and influences in vitro the enzymes involved with basement membraneremodeling.(AU)