This study aims to develop an in vitro co-culture system of in situ goat preantral follicles with bone marrow-derived mesenchymal stem cells (BM-MSC), evaluating the influence of these cells on follicular growth, rate of activation and morphologically normal follicles. Fragments of ovarian cortex were cultured for 1 or 7 days in the presence of BM-MSC (BM-MSC+) and absence of BM-MSC (BM-MSC−). Histological sections of the fragments were analysed and data were obtained regarding morphological classification, survival rate of morphologically normal follicles and rate of follicular activation. Culture medium on days 1 and 7 was also sampled for nitrite concentration and reduced glutathione activity. There was a reduction (P < 0.05) in the percentage of morphologically normal follicles in the BM-MSC+ compared with the fresh control only on the seventh day of culture. When comparing treatments, on the seventh day of culture, a higher rate of morphologically normal preantral follicles was observed in BM-MSC+ (P < 0.05). In both treatments, primordial and developing follicle rates were similar to the fresh control (P > 0.05). When comparing treatments with each other, as well as with the fresh control, no differences were observed in follicular diameter (P > 0.05) or nitrite concentration (P > 0.05). The concentration of reduced glutathione was lower on the seventh day of co-culture in both treatments (P < 0.05). In conclusion, co-culture had no influence on follicular or oocyte development. However, it was critical to maintain the survival of preantral follicles during 7 days of culture.