week old Hormad12/2 mouse testis. (K) Apoptotic index was calculated in wild-type (WT) and Hormad12/2 mouse testis (KO) mice. Knockout testes had significantly higher apoptotic index at 2 weeks of post-natal life and beyond. Error bars represent the standard error of the mean. Error bars represent the standard error of the mean. Student’s t test was used to calculate P values. P value was less than 0.001 at every time point except one week. Scale bar: 100 mM. Found at: doi:10.1371/journal.pgen.1001190.s003 (3.02 MB TIF) Figure S4 No germ cell loss in the Hormad12/2 ovary. At post- natal day 8, primordial, primary, and secondary follicles were detected in wild-type (A) and the Hormad12/2 ovaries (B). Anti- Lhx8 antibody was used to detect germ cells (brown stain). Histogram represents primordial follicles (PF), primary follicles (PrF), and a total number of secondary follicles (SF) in the wild- type (WT) and mutants (KO) (C). Every fifth section of wild-type (n = 6) and Hormad12/2 ovaries (n = 5) were counted. Error bars represent the standard error of the mean. Fisher’s exact t test was used to calculate P values. P value between mutant and wild-type References 1. Page SL, Hawley RS (2004) The genetics and molecular biology of the synaptonemal complex. Annu Rev Cell Dev Biol 20: 525–558. 2. Bailis JM, Roeder GS (1998) Synaptonemal complex morphogenesis and sister- chromatid cohesion require Mek1-dependent phosphorylation of a meiotic chromosomal protein. Genes Dev 12: 3551–3563. 3. Klein F, Mahr P, Galova M, Buonomo SB, Michaelis C, et al. (1999) A central role for cohesins in sister chromatid cohesion, formation of axial elements, and recombination during yeast meiosis. Cell 98: 91–103. 4. Loidl J, Klein F, Scherthan H (1994) Homologous pairing is reduced but not abolished in asynaptic mutants of yeast. J Cell Biol 125: 1191–1200. 5. 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