RPA1 is essential for meiosis in males.

(A) Histological analysis of testes from 8-week-old control and tamoxifen-treated Rpa1fl/fl Ddx4-CreERT2 mice. Cross-sections of Stage IX and XII seminiferous tubules are shown. Dash lines indicate missing germ cells. Arrowheads designate the apparently apoptotic spermatocytes (day 12, Stage XII). Lep, leptotene; Zyg, zygotene; Pa, pachytene; M, metaphase spermatocytes; ES, elongating spermatids. Scale bar, 50 μm. (B) Surface spread analysis of spermatocytes from testes at 4 days post-TMX treatment (dpt). (C) Composition of spermatocytes. Three males per timepoint were analysed. ~200 spermatocytes from each mouse were counted and categorized into different spermatocyte types. The percentage (average ± SD) was plotted. (D) Time-dependent progressive loss of spermatocytes in tamoxifen-treated Rpa1fl/fl Ddx4-CreERT2 males. Lines indicate the presence of spermatocytes. Two cell cycle checkpoints (pachytene checkpoint at stage IV and spindle assembly checkpoint at stage XII) are shown. Note that zygotene-like is separated from zygotene for illustration purpose and is not a separate stage of meiosis.