^, :;■;•,>;: . ;.;. . , V,:-. ■ 143 



tightly bound clusters (Fig. 32). These bundles of spermatozoa are similar to the 

 spermatozeugmata or spermatophores described in a number of internally fertilizing 

 teleosts (reviewed by Grier 1981). The distinction between spermatophores and 

 spermatozeugmata requires study of encapsulating secretory products and the 

 association of sperm with Sertoli cells; I have not examined the sperm morphology 

 in sufficient detail to resolve the exact nature of the sperm bundles (to adequately 

 do so requires transmission electron microscopy). However, I have observed the 

 outwardly projecting sperm heads that are characteristic of spermatozeugmata 

 (Grier 1981), and thus I tentatively identify ageneiosid sperm bundles as this type. 

 Each spermatozoan has a round nucleus, a short midpiece, and a very long 

 flagellum. Grier et al. (1990) briefly discussed previous generalizations that the 

 midpiece and/or sperm nucleus of viviparous teleosts are elongated. However, 

 Grier and his associates (1981, 1990) found that elongation of the midpiece is not 

 always present in viviparous species (for the purpose of comparing sperm 

 morphology I do not distmguish between ovoviviparity and viviparity [Wourms 

 1981]). Ageneiosids provide an additional exception to the generaUzation that 

 internal fertilization in teleosts is coupled with an elongation of the anterior region 

 of the spermatozoan. - r: • ; 



I have been unable to adequately study the structure of the posterior region 

 of the ageneiosid testis. In ictalurids, the cells of the posterior region are 

 predominately columnar in appearance (Sneed and Clemens 1963), and they are 

 known to be involved in steroid secretion (Rosenblum et al. 1987). 

 Spermatogenesis does not occur in this region. The caudal testicular region of 

 ageneiosids is superficially similar to that of ictalurids. In breeding males, the entire 

 posterior region becomes greatly enlarged, forming a cylindrical tube. In one 

 histological preparation, the lumen was extensive and filled with spermatozoa 

 suspended in an amorphous substance. Possibly, the enlarged posterior region of 

 the testes secretes a mucoid plug, as suggested by Ihering (1937). It may also be 



