Investigation of Osteopontin (OPN) Expression in Dromedary Camel (<i>Camelus dromedarius</i>) in the First Trimester of Pregnancy

Osteopontin (OPN) is a phosphorylated acidic glycoprotein that serves various purposes across various systems. Principally, it aids in adhesion and signaling. It is an important protein related to reproduction, which has been discovered in several species, among which is the dromedary camel, where it has been detected in the endometrium and conceptuses at the time of implantation. The objective of this research is to investigate and examine the expression patterns of OPN mRNA and protein in both endometrial uterine horns with their associated fetal membranes during the first trimester of camel pregnancy. Endometrial and fetal membranes were collected from eight pregnant female camels during the first trimester of pregnancy (Days 70–110 of pregnancy). The temporospatial expression of OPN was studied in endometrial tissues and their conceptuses from the left uterine horn (LUH) and right uterine horn (RUH) using quantitative real-time PCR (qRT-PCR) and immunohistochemistry (IHC) techniques. The results showed a gradual increase in OPN mRNA expression with advancing pregnancy in both LUH and RUH of endometrial and fetal membranes tissue. OPN protein was predominantly found in the uterine luminal epithelium (LE) and fetal trophectoderm (Tr), stroma, and uterine glands. In conclusion, our findings demonstrate that OPN is consistently present in both the endometrium and fetal membranes throughout the first trimester of pregnancy. This observation advances previous knowledge by confirming OPN expression even during the early first trimester, suggesting its crucial role in supporting embryo attachment, implantation, and placentation processes in the dromedary camel.