Of these factors, Ranbp9 and Morf4l1 (Mrg15), which are differentially expressed between step 2 and step 8 round spermatids, have been shown to be essential for spermiogenesis (Fig. 6d, e), demonstrating the potential value of this dataset.41,42 Interestingly, we observed that a splicing factor hnRNPL, whose mutation is associated with non-obstructive azoospermia in humans,43 was significantly differentially expressed between zygotene and early pachytene spermatocytes, indicating that it could control meiosis through splicing regulation of target genes. This evidence concerns the gene MORF4L1 and Azoospermia.