The Zebrafish in Toxicology/Ovary staging

an interactive version of this book is available here back to Table of Contents - The Zebrafish in Toxicology Reproduction - Ovary Normal Histology ovary development previtellogenic stageing: sequential images previtellogenic stageing: sequential images Six subsequent previtellogenic (intermediate) stages of ovary maturation, as recorded in juvenile zebrafish 6 weeks of age, and classified according to the most predominant oocyte maturation stage. For structure analysis of these images, see structure – immature. An example of the application of this classification is the evaluation of the effects of effluent of a sewage treatment works (Eindhoven, the Netherlands) in zebrafish, shown at the bottom of this page. File:9911jovamats0wb.jpg Coronal section of a juvenile female zebrafish, age 6w; H&E staining (all images) stage 0 undifferentiated gonad File:9911jovamats1wb.jpg stage 0-1 appearance of stage 1 primary oocytes (previtellogenic, small rim of cytoplasm) File:9911jovamats2wb.jpg stage 1 predominance of stage 1 primary oocytes File:9911jovamats3wb.jpg stage 1-2 intermediate stage, mixed occurrence of stage 1 and stage 2 primary oocytes File:9911jovamats4wb.jpg stage 2 initial growth of oocytes: increase of nucleus size, increase of cytoplasm volume, cytoplasm becomes basophilic File:9911jovamats5wb.jpg stage 3 appearance of stage 3 oocytes (further increase of cytoplasm to approx. 100 µm cell diameter, bright spotting in the cytoplasm as indication of endogenic vitellogenin accumulation) File:Ovastgrwb.jpg Application of the ovary maturation classification in the evaluation of the effects of effluent of a sewage treatment works (Eindhoven, the Netherlands) in zebrafish. Adult zebrafish and their progeny were exposed to either control Dutch Standard Water (DSW ¾-, blue line ), estradiol (E2, ¾-, red line ), or sewage effluent ( ¾-, magenta line ) for 6 weeks. Shown is the average of the percentages of the total number of animals in the respective groups (2-5 groups per treatment, 30-50 individuals per group) in each class. It appeared that exposure of juveniles to either E2 or sewage effluent inhibited ovary maturation, compared to control animals