To study the important regulatory factors promoting follicle growth into dominant follicle and their expression pattern in bovine follicular development,the largest follicle(8—10 mm) and the second largest follicle(5—8 mm)were acquired and the estrogen(E₂) and progesterone(P) concentrations in follicular fluid were determined to define the dominant follicles( DF) and subordinate follicles( SF).Granulosa cells in DF and SF were scraped,total RNA was extracted,and then libraries were constructed,and sequenced by Illumina platform.mRNA sequences were obtained by comparing the sequenced sequences with the bovine reference genome database using SOAP V2. 0 software. Differential expression of the obtained mRNA was analyzed by DESeq 2 software,and the up-regulated genes were studied by GO analysis and KEGG pathway analysis and finally real-time fluorescent quantitative PCR was used to verify the selected representative up-regulated genes.A total of 32 346 genes were obtained through sequencing,and 194 genes were significantly up-regulated in DF granulosa cells.GO analysis results showed that all the up-regulated genes were divided into 33 groups of 3 categories,and 60.6% of the genes were involved in biological process. Genes related to cellular component accounted for 21.2%,the most of which(31)were involved in cytoplasm.The genes related to molecular function accounted for 18.2%,and 18 genes were involved in metal ion binding.KEGG pathway analysis revealed a total of 4 pathways,among which the most significant gene enrichment was axon guidance pathway.Real-time fluorescent quantitative PCR results showed that the relative expression of cytochrome P450 19A1 gene(CYP19A1) in DF granulosa cells was significantly higher than that in SF(P<0.01),and the relative expressions of thioredoxin binding protein gene(TXNIP),brain expression linked X2(BEX2) and serine protease 35(PRSS35) genes in DF granulosa cells were significantly higher than those in SF(P<0.05),which was consistent with Illumina sequencing.In summary,CYP19A1,TXNIP,BEX2,and PRSS35 may promote follicular development and cause follicular ovulation in cattle.