Fig. 4
Female gonad of the brown bullhead (Ameiurus nebulosus) inhabiting the oxbow lake of the Vistula River, Poland; A: in early vitellogenesis with oocytes in previtellogenesis (P) and vitellogenesis (V), March. Scale bar 100 μm; B: spawning gonad with mature oocytes and post-ovulatory follicles (star), April. Scale bar 100 μm; C: developing gonad containing oocytes in previtellogenesis (P), vitellogenesis (V), and degenerating oocytes (D), May. Scale bar 200 μm; D: post-spawning gonad with degenerating oocytes (D) and post-ovulatory follicles (star), June. Scale bar 100 μm; E: degenerating oocytes (D) in the gonad preparing for the next season with oocytes in previtellogenesis (P) and vitellogenesis (V), August. Scale bar 100 μm; F: single oocytes in vitellogenesis (V) between oocytes in previtellogenesis (P) and degenerating oocytes (D), November. Scale bar 200 μm.
