library_construction_protocol: At postnatal day (PD) 7, ovaries from euthanized control mice (n=3) and from Wls cKO mice (n=8) were collected. Ovaries were treated with a CTK solution (consisting of 0.25% trypsin (Thermo), 0.1% collagenase type IV (Gibco), 20% KSR (Invitrogen) and 1 mM CaCl2 in PBS) for 30 min at 37°C, then further treated with Accutase (Nacalai) at 37°C for 15 min. The reaction was halted by adding L-15 medium with 0.1% penicillin-streptomycin and 5% FBS, and the cells were dissociated by pipetting. The cell suspension was filtered through 70 μm cell strainers, followed by centrifugation at 400 g for 5 min and resuspension in sorting buffer (7.5% BSA (Life Technologies) in PBS). Blocking was performed with rat IgG (5 mg/mL, I8015, Sigma-Aldrich) for 15 min on ice. Subsequently, cell surface staining was conducted using anti-ckit-APC (1:50, 105812, BioLegend) and anti-CD45-Alexa Fluor 488 (1:200, 103122, BioLegend) for 15 min on ice. After centrifugation at 400 g for 5 min, cells were resuspended in sorting buffer. Prior to single-cell sorting by flow cytometry, samples were passed through 40 μm cell strainers, and DAPI (1:10,000) was added. Control and Wls cKO samples were each sorted using MoFlo Astrios EQ with Summit v 6.3.0. software (Beckman Coulter) into 384-well plates containing 286 tdTomato-positive somatic cells and 95 ckit-positive oocytes. DAPI-positive dead cells and CD45-positive leukocytes were excluded. Library preparation for RamDA-seq was performed according to a previously report. However, to reduce reagent costs and rRNA-derived sequencing reads, the method was modified as follows: To suppress rRNA-derived cDNA synthesis, 0.008 units/µl XRN-1 (NEB) was added to the genomic DNA digestion mix, and the reaction was performed at 30°C for 5 min. To reduce reagent costs, a liquid dispenser Mantis (Formulatrix) was used to perform the reaction up to second strand synthesis at 1/10 the reaction volume. After that, 2.5 μl 0.8 X Tagment DNA Buffer (Illumina) diluted with RNase-free water was added to 0.5 μl of the second strand synthesis products for dilution. Then, 0.5 μl Amplicon Tagment Mix (Illumina) was added to 1.5 μl of the diluted product, and tagmentation was performed at 55°C for 10 min. After that, the library was prepared using 1/10 the reaction volume according to the Nextera XT DNA Library Prep Kit (Illumina) procedure. Twelve PCR cycles were performed. Somatic and oocyte library products were collected separately in equal volumes of 1 μl/well. Subsequently, 50 μl of each sample was fractionated from the equal mixed library, purified with 1.2X AMPureXP (Beckman Coulter), and eluted with 25 μl TE. To prevent large discrepancies in the number of sequencing reads per cell between somatic and oocyte cells, purified libraries were mixed to ensure a constant average molar per cell type using the quantitative results from the Bioanalyzer Agilent High-Sensitivity DNA Kit and the ratio of the number of cells sorted (somatic cells: oocytes = 286:95). The pooled library of 2.3 pM was sequenced in single end read 76 cycles using NextSeq 500 High Output Kit v2.5.