Alterations in the integument of masculinized females ofArmadillidium vulgarecaused by the implantation of androgenic glands from normal males involve both pigment cells and epidermal cells with respect to the intracellular structure and the ommochrome content. Epidermal cells beneath the cuticle of masculinized females are thicker than those of normal females, having a number of small secretory granules and well developed rough endoplasmic reticulum in the cytoplasm. As a result of epidermal cell thickening, pigment cells are more widely separated from the cuticle in masculinized females than in normal females. The ommochrome content in the integument of masculinized females, which was initially the same as that of normal females, increased with each postoperative stage and coincided with that of male integument by the fourth postoperative stage. The observations suggest that the slate grey color characteristic of the male body, shown during masculinization of females after the implantation of androgenic glands, is possible caused by both the structural changes in epidermal cells and alterations in the ommochrome content in pigment cells.