Fig. 4

Chk2 mutation rescues fertility of Sws1 and Swsap1 mutant females. a Ovary to body weight ratios of Sws1^−/− Chk2^−/− and Swsap1^−/− Chk2^−/− adult mice are similar to controls, but testis to body weight ratios remain significantly reduced. Female mice: Control, n = 16; Chk2^−/−, n = 7; Sws1^−/−, n = 5; Sws1^−/− Chk2^−/−, n = 3; Swsap1^−/−, Swsap1^−/− Chk2^−/−, n = 3. Male mice: control, n = 15; Chk2^−/−, n = 14; Sws1^−/−, n = 4; Sws1^−/− Chk2^−/−, n = 2; Swsap1^−/−, n = 10; Swsap1^−/− Chk2^−/−, n = 5. ns not significant; *P ≤ 0.05; **P ≤ 0.01; ***P ≤ 0.001; Student’s t-test; two-tailed. b–d Adult Swsap1^−/− Chk2^−/− ovaries have follicles at various stages of oocyte development, unlike Swsap1^−/− ovaries. Primordial follicles in Chk2^−/− and Swsap1^−/− Chk2^−/− are highlighted in b in insets and by arrows in c; primordial follicles in Chk2^−/−, Sws1^−/− Chk2^−/− and Swsap1^−/− Chk2^−/− are quantified in d. Sections were stained with hematoxylin and eosin (H&E) in b, and with hematoxylin and an antibody for DDX4/Vasa in c. Scale bar, 500 μm and 50 μm insets. Mice: control, n = 4; Chk2^−/−, n = 5; Sws1^{-/ -}, n = 4; Sws1^−/− Chk2^−/−, n = 3; Swsap1^{-/ -}, Swsap1^−/− Chk2^−/−, n = 3. **P ≤ 0.01; ***P ≤ 0.001; ****P ≤ 0.0001; Student’s t-test, two-tailed. e MLH1 foci are reduced in Swsap1^−/− Chk2^−/− oocytes from mice at embryonic day 18.5 similar to the level observed in Swsap1^−/− oocytes, and synaptic defects are also observed in the majority of Swsap1^−/− Chk2^−/− oocytes as also seen in Swsap1^−/− mice (open circles). Mice: Control, Swsap1^−/−, n = 1 (from Fig. 3i); Swsap1^−/− Chk2^−/−, Chk2^−/−, n = 1. ****P ≤ 0.0001; Mann–Whitney test, one-tailed. f Swsap1^−/− Chk2^−/− spermatocytes that progress to mid-pachynema and beyond are increased in number relative to that observed in Swsap1^−/− mice, as demonstrated by histone H1t staining. Total number of mid-pachytene, late-pachytene, and diplotene spermatocytes divided by the total number of spermatocytes analyzed from adult testes. Mice: Control, Swsap1^−/−, from Fig. 2a; Chk2^−/−, Swsap1^−/− Chk2^−/−, n = 2. *P ≤ 0.05; ****P ≤ 0.0001; Fisher’s exact test, two-tailed. g Spermatocytes in adult Swsap1^−/− Chk2^−/− mice mostly arrest at pachynema, but tubules occasionally contain round and elongated spermatids (blue rectangles and insets). Sections were stained with H&E. Scale bars, 100 μm (top panel), 50 μm (bottom panel), and 20 μm (inset). Error bars in a, d, e, mean ± s.d