Fig. 3: Mouse models mimicking the patients’ mutation exhibited defects in crossover formation.

a Representative images of testis and epididymis morphology from 2-month-old WT and Redic1 KI mice. Scale bar: 2 mm. b, c Ratios of the testis to body weight (b) and sperm counts per epididymis (c) in 2-month-old WT and Redic1 KI mice. The data are from three adult mice for each genotype and represent the mean ± SD. **P < 0.01; ***P < 0.001; two-tailed Student’s t-test. d Representative images of hematoxylin and eosin-stained testicular and epididymal sections from adult Redic1 KI and WT mice. The metaphase I spermatocytes (MI) and spermatids (spt) are indicated by the arrows. Scale bars: 50 μm. e Representative metaphase I (MI) spermatocytes from adult WT and Redic1 KI mice stained with Giemsa. The bivalent chromosomes in Redic1 KI mice are indicated by the arrows. Scale bars: 10 μm. f Quantification of bivalents per metaphase I spermatocyte from 2-month-old WT and KI mice. n, the total number of MI cells scored from two animals for each genotype. Data are presented as the mean ± SD. ***P < 0.001; Welch’s t-test. g Representative spreads of mid-pachytene spermatocytes from WT and KI mice stained for SYCP3 (magenta), MLH1 (green), and H1t (white). Scale bars: 10 μm. h Quantification of MLH1 foci in mid-pachytene spermatocytes. n, the total number of cells analyzed from two animals per genotype. The bars represent mean ± SD. ***P < 0.001; Mann–Whitney test. i Representative spreads of mid-pachytene spermatocytes from WT and KI mice stained for SYCP3 (magenta), HEI10 (green), and H1t (white). Scale bars: 10 μm. j Quantification of HEI10 foci in mid-pachytene spermatocytes. n, the total number of cells analyzed from three animals per genotype. The bars represent mean ± SD. ***P < 0.001; Mann–Whitney test. k Representative images of the histology of ovaries from WT and Redic1 KI female mice at the indicated ages. The primordial (green arrows), primary (yellow arrows), and secondary (magenta arrows) follicles are indicated in the ovarian sections of 5 dpp and 14 dpp mice. Scale bars, 50 μm. l Representative images of surface-spread oocytes from 18.5 dpc WT and Redic1 KI mice stained for MLH1 (green) and SYCP2 (magenta). Scale bars: 10 μm.