RPL10L (ribosomal protein L10 like) is a testis-specific ribosomal protein component derived from retrotransposition of the X-linked RPL10 gene 1. During male spermatogenesis, RPL10L compensates for the transcriptional inactivation of RPL10 through meiotic sex chromosome 14 (MSCI), enabling the transition from prophase to metaphase during meiosis I 2. As a structural component of the male germ cell-specific ribosome, RPL10L regulates biosynthesis and folding of male germ cell-specific proteins essential for sperm formation, with distinct ribosomal properties compared to somatic ribosomes 3. Loss-of-function mutations in RPL10L cause severe male infertility phenotypes. Homozygous missense mutations impair protein stability and associate with severe oligozoospermia, while biallelic variants have been identified in azoospermia patients 45. RPL10L expression is conserved across species in male germ cells 6. Beyond reproductive function, RPL10L has been implicated as a prognostic biomarker in liposarcoma pathogenesis 7. These findings establish RPL10L as critical for male fertility through its compensatory role in meiotic ribosome function and identify mutations as a novel cause of heritable male factor infertility.