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.
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stage 0 undifferentiated gonad |
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stage 0-1 appearance of stage 1 primary oocytes (previtellogenic, small rim of cytoplasm) |
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stage 1 predominance of stage 1 primary oocytes |
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stage 1-2 intermediate stage, mixed occurrence of stage 1 and stage 2 primary oocytes |
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stage 2 initial growth of oocytes: increase of nucleus size, increase of cytoplasm volume, cytoplasm becomes basophilic |
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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) |
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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 |
