Abstract
Avian species exhibit a notable asymmetry in their reproductive systems, with the left ovary maturing into a functional organ and the right ovary degenerating. This asymmetry is widespread across bird species, yet the molecular underpinnings of right ovarian degeneration are not fully understood. In this study, we constructed a cellular atlas of the degenerating right ovary in geese through single-cell transcriptome sequencing (scRNA-seq), revealing distinct cellular compositions and gene expression profiles. Meanwhile, we identified variations in the rate of right ovarian degeneration among individuals, which may influence the gene expression profiles of the hypothalamic-pituitary-ovary (HPO) axis, particularly the related pathways involved in steroid hormone secretion and follicular development of the left ovary. Genomic sequencing combined with transcriptomic data, led to the identification of LHX9 and ARID5B as potentially associated with the rate of right ovarian degeneration in avian species. Our study provides a comprehensive cellular and molecular understanding of the degeneration process in the right ovary of geese. The identification of LHX9 and ARID5B as potential regulators of degeneration rate offers new insights into the genetic factors influencing avian reproductive asymmetry. These findings have implications for improving reproductive efficiency in geese and contribute to the broader understanding of the evolution of avian reproductive systems.