In order to study the mechanism of follicle growth and maturation, and also to supplement the criteria identifying the follicle state of normal of atretic, the histochemical investigation on the ovarian follicles according to the ovarian cycle of mouse, rat and pig has been done. The intercellular space of granulosa cells, especailly Call-Exner body, and follicular fluid in the antrum showed positive to PAS, and blue stain by trichrome dye. The resutls suggest that the mucous polysaccharide was synthesized by the granulosa cells, and secreted into the antrum through Call-Exner body so as to be the components of the follicular fluid as the follicles proceeded to growth and maturation. The further the follicles proceeded to atresia the more densely their theca externa were stained blue by follicles proceeded to atresia the more densely their theca externa were stained blue by trichrome dye, and the more densely the granulosa cells were stained red by oil red 0 dye. Therefore, these staining methods can be applied to the criteria identifying the follicle atresia.