Reduced sperm counts in guppies (Poecilia reticulata) following exposure to low levels of tributyltin and bisphenol A

There is increasing evidence that normal male reproductive function can be disrupted by exposure to pollutants in the environment that can exogenously mimic, antagonize or block sex-hormone function. One possible consequence of exposure to these xenobiotics is disruption to spermatogenesis, but resu lts thus Far provide only indirect and inconsistent evidence. In this stud! : we exposed adult male gruppies (Poeciliidac: Teleostei) to environmentall y relevant levels of the common xenobiotics tributyltin (11.2-22.3 ng l(-1) ) and bisphenol A (274-549 mu gl(-1)) in experimental aquaria. After 21 day s of exposure, we Found significant declines (by 40 75%) in total sperm cou nts for male fishes exposed to tributyltin and bisphenol A compared with co ntrols. This short-term decline in sperm count is unlikely to be the result of endocrine-mediated alteration of the germ line, and we found no change in testis size or sperm lengths: between treatments. However, Sertoli cells , which facilitate the transport of maturing sperm into the testicular defe rent duct (where they are stored prior to ejaculation), are directly sensit ive to xenobiotic action and it is therefore possible that spermatogenesis was inhibited through in vivo interference with normal Sertoli-cell functio n.