Changes in ovarian histology of the sapphire devil (Chrysiptera cyanea) with a pellet on the calvaria. Ovaries were collected at 1 and 4 weeks after the onset of the experiment. A cross section of an ovary (CSO) of (A) the control pellet group after 1 week, (B) CSO of the treatment group after 1 week, (C) CSO of the control pellet group after 4 weeks, and (D) CSO of the treatment group after 4 weeks. ODS, oil droplet stage; PNS, peri-nucleolus stage; TYS, tertiary yolk stage. Scale bar = 200 μm.