Follicular development and ovary aging: single-cell studies

Abstract Follicular development is a critical process in reproductive biology that determines the number of oocytes and interacts with various cells within the follicle (such as oocytes, granulosa cells, cumulus cells, and theca cells), and plays a vital role in fertility and reproductive health because of the dogma of a limited number of oogonia. Dysregulation of follicular development can lead to infertility problems and other reproductive disorders. To explore the physiological and pathological mechanisms of follicular development, immunology-based methods, microarrays, and next-generation sequencing have traditionally been used for characterization at the tissue level. However, with the proliferation of single-cell techniques, research has uncovered unique molecular mechanisms in individual cells that have been masked by previous holistic analyses. In this review, we briefly summarize the achievements and limitations of traditional methods in the study of follicular development. Simultaneously, we focus on how to understand the physiological process of follicular development at the single-cell level and reveal the pathological mechanisms and relevant intervention targets. Moreover, we also delineate the limitations and application prospects of single-cell sequencing in follicular development research.