To study the possible roles of HSP10 in the follicular development. In this study, we examined the expression of HSP10 during the follicular development in human ovaries and cultured mouse follicles as well as its functional relevance with PCOS. Ovary tissues from normal adults (n = 3) were obtained with consents. Mouse early antral follicles (diameter: 220-250 mum) were cultured for 3 days in vitro. Western Blot and immunohistochemistry were used to determine the HSP10 expression and localisation during follicular development in vivo and in vitro. HSP10 protein was detected only in oocytes from human preantral follicles, whereas in antral follicles, it was localised in oocytes, granulosa cells, theca cells and stroma cells. Furthermore, in cultured mouse antral follicles, a similar trend of HSP10 expression during follicle development was observed. HSP10 expression was increased as larger area and higher level of density during follicular development both in human and mouse follicles cultured in vitro. Our previous studies showed that HSP10 was highly expressed in normal ovaries compared with those from PCOS. The mouse early antral follicle culture approach may help to understand the role of HSP10 in pathophysiological development of PCOS.