Biology of Reproduction, Vol 25, 143-146, Copyright © 1981 by Society for the Study of Reproduction

Localization of Testicular Plasminogen Activator in Discrete Portions (Stages VII and VIII) of the Seminiferous Tubule

¹ Department of Biochemistry and Banting and Best Department of Medical Research, University of Toronto, Toronto, Ontario, Canada M5G 1L6
² Institute of Biomedicine, Department of Anatomy, University of Turku, 20520 Turku 52, Finland

We have previously reported that rat Sertoli cells in culture produce and secrete plasminogen activator, a highly specific protease, and that FSH stimulates these processes. We have postulated that localized proteolysis elicited by plasminogen activator may be implicated in the restructuring of the seminiferous tubule which occurs when spermatocytes in early prophase of meiosis are translocated from the basal to the adluminal compartments. To test the conjecture further, we isolated tubule segments at different stages of the cycle of the seminiferous epithelium, using the transillumination procedures of Parvinen and Vanha-Perttula, and we determined levels of plasminogen activator in extracts or culture medium in which segments were incubated for 20 h. We found that levels of plasminogen activator were significantly higher in segments at stages VII and VIII of the cycle and that amounts released into the medium by these segments were more than 100-fold greater than those released by segments of seminiferous tubule from any other stage. Segments with seminiferous epithelium at stages VII and VIII are the regions of the tubule in which spermiation occurs, and in which movement of Sertoli cell cytoplasmic processes around leptotene spermatocytes takes place. We advance the hypothesis that plasminogen activator is intimately related to the localized restructuring which takes place as spermatocytes in meiosis are prepared for translocation into the adluminal compartment and as spermiation occurs at stages VII and VIII in the seminiferous epithelium of the tubule.

Note:
ACKNOWLEDGMENTS We thank Drs. F. E. Smith and P. S. Tung for their collaboration and interest in these experiments and Drs. J. H. Dorrington and R. E. Gore-Langton for their helpful criticisms and suggestions. This work was supported by grants from the Canadian Medical Research Council and the Finnish Medical Research Council (Academy of Finland).

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