102 



Fishery Bulletin 94(1). 1996 



Postovulatory follicles estimated to be 6 to 12 hours 

 old showed distinct signs of cellular degeneration 

 (Fig. 4, C and D). They were smaller and less convo- 

 luted, and there were some irregular cells and pyc- 

 notic nuclei in the granulosa and thecal layers. The 

 granulosa no longer showed a well-organized align- 

 ment of cell walls or nuclei and was in obvious con- 

 tact with the theca. At this stage the thecal layer 

 appeared thicker. 



Postovulatory follicles estimated to be 12 to 18 

 hours old showed advanced cellular degeneration 

 (Fig. 4, E and F). They were considerably smaller 

 and lacked the distinctly convoluted appearance of 

 previous stages, but still had follicular cavities. A 

 thicker thecal layer surrounded the much thinner 

 granulosa cell layer, and the two were in close con- 

 tact. The granulosa layer was still distinguishable, 



although it now consisted of a few irregular cells with 

 pycnotic nuclei. 



Postovulatory follicles estimated to be 18 to 24 

 hours old showed signs of the final stages of degen- 

 eration (Fig. 4, G and H). The follicle was smaller 

 still, not convoluted but elongate, and had a follicu- 

 lar cavity. The granulosa layer consisted of few cells, 

 was very thin, and not clearly separable from the 

 thicker thecal layer. Prominent, sharply staining 

 pycnotic nuclei were apparent in the degenerating 

 thecal layer. 



Several observations indicated that postovulatory 

 follicles are histologically detectable for no more than 

 24 hours after spawning. Postovulatory follicles of 

 only a single degenerative stage were found in ova- 

 ries sampled throughout the day, and the stage of 

 degeneration was consistent among ovaries sampled 



