Circular RNAs (circRNAs) are a class of animal non-coding RNAs and play an 
impor-tant role in animal growth and development. However, the expression and 
function of circRNAs in the pituitary gland of sheep are unclear. Transcriptome 
profiling of circRNAs in the pituitary gland of sheep may enable us to 
understand their biological functions. In the present study, we identified 
10,226 circRNAs from RNA-seq data in the pituitary gland of prenatal and 
postnatal sheep. Reverse transcription PCR and DNA sequencing analysis confirmed 
the presence of several circRNAs. Real-time RT-PCR analysis showed that sheep 
circRNAs are resistant to RNase R digestion and are expressed in prenatal and 
postnatal pituitary glands. GO and KEGG enrichment analysis showed that host 
genes of differentially expressed circRNAs are involved in the regulation of 
hormone secretion as well as in several pathways related to these processes. We 
determined that numerous circRNAs interact with pituitary-specific miRNAs that 
are involved in the biologic functions of the pituitary gland. Moreover, several 
circRNAs contain at least one IRES element and open reading frame, indicating 
their potential to encode proteins. Our study provides comprehensive expression 
profiles of circRNAs in the pituitary gland, thereby offering a valuable 
resource for circRNA biology in sheep.