Regulation of spermatogenesis by estrogen in zebrafish

Abstract

Summary The aim of this thesis is to give an insight into how hormones in general, and estrogen specifically, regulate spermatogenesis in zebrafish. First, information on the spermatogenic process, the somatic and germinal cell types involved in this process and the main hormonal substances that regulate spermatogenesis, is reviewed. This information can be found in chapters one, two and three. Then, the research that is currently carried out at the Developmental Biology group at Utrecht University is introduced in chapter four. The questions, or problems, that are still open for investigation are presented. The information and research on the topic of hormonal control of spermatogenesis is not only of fundamental interest, but also has an applied background, which will be discussed as well. Chapter five presents how this research may contribute to gain knowledge that may yield a healthier environment and maybe even an improved economy. In the concluding chapter six, the experiment that was carried out during my internship is described. This experiment was performed with the objective to clarify if the estrogen effects on spermatogenesis in zebrafish in vivo are direct effects on the testis or indirect effects via feedback mechanisms on the brain and pituitary level. This was done by incubating testis tissue with estrogen in vitro using a primary tissue culture system, in order to compare the results with those obtained in vivo.