gamma-Glutamyl transpeptidase as a possible marker of Sertoli cells in fish testes for studies of xenoestrogens.

Estrogenic chemicals are known to have marked effects on the reproductive system of male fish. Finding useful markers of reproductive effects are therefore of great importance and interest. gamma-Glutamyl transpeptidase (gamma-GTP) is a possible marker of Sertoli cells in testes of fish. In the present study we have examined the relationship between the activity of gamma-GTP and the histological structure of the Sertoli cells in testes of five fish species (guppy, Poecilia reticulata; platyfish, Xiphophorus maculatus; eelpout, Zoarces viviparus; rainbow trout, Oncorhynchus mykiss; flounder, Platichthys flesus). In general we found that the more distinct the Sertoli cells the higher the activity of gamma-GTP.