Abstract
The activation, growth, and maturation of oocytes to an ovulatory phase, termed folliculogenesis, is governed by the orchestrated activity of multiple specialized cell types within the ovary; yet, the mechanisms governing diversification and behavior of discrete cellular sub-populations within follicles are poorly understood. We use bulk and single-cell RNA sequencing to distinguish the transcriptional signature of prospectively isolated granulosa and theca/stroma cell subsets within human antral follicles derived from xenografts or ovaries. The analysis deconstructs phenotypic diversification within small (<4 mm) antral follicles, identifying secreted factors that are differentially enriched between mural and oophorus granulosa cells, and segregating stromal/support and steroidal activity between theca externa and interna, respectively. Multiple factors are differentially expressed in follicles of xenograft versus ovarian origin. These data capture a high-resolution transcriptional signature of granulosa and theca subpopulations and provide a systems-level portrait of cellular diversification in early antral human follicles.