**5. Conclusions**

In conclusion, the present study identified PRDX1, 2, 6, and 5 as major antioxidant genes and proteins in neonatal gonocytes, essential for the survival of the cells, especially under conditions of oxidative stress. Moreover, gonocytes were more sensitive to Conoidin A e ffects than spermatozoa, whereas they were less sensitive to the inhibition of the PLA2 activity of PRDX6 than spermatozoa, suggesting a di fference in the antioxidant machinery of gonocyte and spermatozoa. Further studies will

be needed to examine the possibility that ROS, endogenous or produced by Sertoli cells, at non-toxic levels, might play a role in the regulation of neonatal gonocyte di fferentiation.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/2076-3921/9/1/32/s1, Table S1: Relative gene expression of antioxidant genes expressed in rat PND3 gonocytes and PND8 spermatogonia. The results represent the mean ± SEM of 3 independent RNA samples for each age, each made from cells isolated in multiple animals. There was no significant di fference between the two types of germ cells for any of the genes. A few genes presenting a signal intensity below 20 were not included.

**Author Contributions:** A.B. performed the experiments presented in Figures 2–7, while G.M. performed the gene array experiments presented in Figure 1. M.C. and C.O. designed the experiments, analyzed the results, and M.C. prepared the manuscript. A.B., C.O. and M.C. revised the final version of the manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was supported in part by funds from a gran<sup>t</sup> from the Canadian Institutes of Health Research (CIHR) (Operating gran<sup>t</sup> # MOP-133456 to MC and # MOP-133661 to CO), a gran<sup>t</sup> from the Natural Sciences and Engineering Research Council of Canada (NSERC) (Discovery Grant # 386038-2013) and funds from the USC School of Pharmacy to MC.

**Acknowledgments:** We thank Maria Celia Fernandez for her assistance in setting up the bodipy method with A.B.

**Conflicts of Interest:** The authors declare no conflict of interest.
