Transcriptome profiling of granulosa and theca cells during dominant follicle development in the horse.

This research paper analyzes the gene expressions associated with the growth and preovulatory maturation of equine dominant follicles. The findings include identification of unique expression profiles at different stages of follicle development, particularly within granulosa cells (GCs) and theca cells (TCs).

Objective of the Study

• The main objective of this study was to understand the global gene expression profiles linked with the growth and maturation of dominant horse follicles before ovulation.

Study Design

• For the study, granulosa cells (GCs) and theca interna cells (TCs) were extracted from horse follicles at different stages of an ovulatory wave. The stages include early dominance, late dominance, and preovulatory stage.
• The samples were later analyzed on a horse gene expression microarray, and the findings were verified using quantitative PCR and immunoblotting/immunohistochemistry procedures.

Findings of the Study

• Significant differences were observed in the expression of transcripts in GCs and TCs during various stages of the ovulatory wave. The most noticeable change was a reduction in records associated with cell division in GCs during both early to late dominance and late dominance to preovulatory stages.
• A high number of genes involved in cell communication/adhesion, antioxidation/detoxification, immunity/inflammation, and cholesterol biosynthesis showed enriched expression during the late dominance to preovulatory stage transition in GCs.
• In TCs, the most prominent change during the transition from late dominance to preovulatory stage was an upregulation of genes associated with immune activation, lipid/amino acid metabolism, and cell proliferation/survival and differentiation.
• The findings highlight distinct gene expression profiles at different stages of follicle development, particularly significant differences between GCs and TCs within each stage.

Conclusion of the Study

• The study concludes with the identification of unique and distinct gene expressions associated with the growth and development of equine dominant follicles at different stages, especially within GCs and TCs.
• The study identified several differentially expressed transcripts (DETs) which have not previously been associated with follicle development in other species, providing new understanding in the field of equine ovarian physiology.