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For the purpose of histological study of ovarian follicules of makoyee ewes, from 100 healthy adult ewes, which were sloughtered in Uromia city abbatoir, ovaries collected in different seasons and in each season 25 specimens taken for study. After performing all processes of preparation for sectioning, serial sections were stained and microscopic investigation carried out. Follicular atresia was observed in all kinds of ovarian follicles and on the base of way of commencing of such process, it is divisible in to two categories, i.e. preantral and antral follicles and as such the way of atresia must be different in between them. We observed that in preantral follicles, atretic signs for the first starting from oocyte and its surrounding follicular cells, whereas in antral follicles, such signs were starting from periphery of follicles, specially granulosa and theca cells. We also observed that, in advanced stage of follicular atresia, cumulus cells showing atretic signs too. It is to be mentioned that, follicular atresia is a complex phenomenon and each category of the ovarian follicles may show one or more kinds of such signs. In this study we found that there is not significant differences between mean distribution of atretic follicles in different stages of growth in different seasons of a year, but in each season there were significant (a=0.01) difference between atretic primary, secondary, and tertiary follicles. Differences of mean distribution of atretic primary and tertiry follicles were not significant, but mean distribution of atretic secondary follicles were significant (a=0.05) with both of them, i.e. primary and secondary