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involved in endocrine functions, but further studies are needed to confirm such a 

 hypothesis. Rosenblum et al. (1987) reported that germ cells were never present in 

 the caudal testicular region oflctalurus nebulosus, in contrast to the condition I have 

 observed in ageneiosids. Roberts (1989b) has suggested that there is a dire need for 

 more studies to elucidate variation of testes morpholo^ among groups of catfishes; 

 this is especially true for the caudal testicular region. 



The ovaries of ageneiosids are smooth-walled, elongate sacs suspended from 

 the dorsal ceiling of the body cavity, just ventral to the kidneys. They are fused at 

 their posterior end. In immature fish the ovaries are small and do not reach the 

 anterior end of the kidney. Posteriorly, the urogenital duct is membranously joined 

 by the urinary duct before exiting the body anterior to the anal-fin origin. The 

 gonopore is deeply invaginated. There is no putative sperm storage structure 

 associated with the female reproductive tract. 



In gravid females the ovaries are greatly swollen and fill a large portion of 

 the coelom. They extend anterior to the kidneys and the posterior apex of the 

 stomach. Internally, the germ cells Une an expanded lumen. In gross appearance, 

 oocytes of many size classes are visible, including small white ones, and very large, 

 vitellogenic eggs. In some specimens examined, ovulation had occurred prior to 

 fixation, and the vitellogenic oocytes loosely filled the ovarian lumen. 



Histologically, the ovaries of immature females resemble those of other 

 catfishes, with randomly distributed oogonia and primary oocytes in a continuum of 

 size classes. The ovaries of gravid females consist of small, nonrecrudescent 

 oocytes, and many large, vitellogenic and yolk vesicle oocytes (terminology after 

 Wallace and Sehnan 1981). The extremely large, yolk-laden follicles are difficult to 

 infiltrate and section with paraffin-based histological techniques, but the procedures 

 used in this study did allow for some crude preparations. In gravid females, 

 spermatozeugmata were observed in the interstices between vitellogenic follicles 

 (Fig. 32). In terms of their shape, the spermatozeugmata appeared unchanged from 



