Adult female zebrafish ovary; H&E staining ovary general structure

Two specimen of normal adult zebrafish ovaries, in different stages of the spawning cycle. The upper specimen shows a high ratio of previtellogenic oocytes, suggestive for an early postspawning stage, whereas the lower specimen contains predominantly vitellogenic oocytes, indicating an intermediate stage. The postspawning condition of the upper specimen is further indicated by the high ratio of postovulatory follicles.
Note, that the upper image shows a lobulated structure, with interlobular spaces that communicate with the lateral oviduct. Thus, the interlobular spaces give way to ovulated oocytes.

Adult female zebrafish ovary, prespawning stage; H&E staining

In a further (prespawning) stage shown here, mature oocytes have ovulated and are collected in the caudal oviduct . This image is suggestive of a prespawning stage.