Characterization of Pre-Theca Cells in Chicken Embryonic Ovaries for Productivity

In poultry, size and quality of the initial pool of primordial follicles, known as ovarian reserve, play a key role in female reproductive lifespan and productivity.The molecular and cellular characterization of the pre-theca cells that drive steroid hormone synthesis and assembly of ovarian reserves in chickens are not well known.A multi-omics approach was used in this study, which analyzed gonadal data of chickens, humans and mice to find and characterize pre-theca cells.The fluorescence in situ hybridization (FISH) was used to verify pre-theca cells.Chicken pre-theca cells were found as early as in the ovary prior to primordial follicle development in single cell mRNA sequencing (scRNA_seq) data analysis.A probe of the CYP11A1 gene verified the presence of pre-theca cells during the formation and activation of primordial follicles.Further, 10 candidate genes that can distinguish pre-theca cells in chicken were identified by the scRNA-seq analysis.The pseudo-time analysis showed that the trajectory of chicken pre-theca cells is linear.On the basis of the data of differential expression, the genes that are significantly up-expressed in female gonads were CYP17A1, TXN, SPON1, BASP1 and APOA1 during chicken's sex determination.Lipid metabolism, steroid synthesis and steroid hormone synthesis were significantly enriched in chicken pre-theca cells.These results indicate that pretheca cells establish an early, specialized steroidogenic microenvironment, and provide a molecular foundation for understanding early ovarian niche formation and reproductive potential in poultry.