Fibroblast growth factor 7 (FGF7) and its receptor FGFR2IIIb during the peri-implantation period of dromedary camels: A comparative analysis between left and right uterine horns.

The peri-implantation period in dromedary camels is a critical phase in pregnancy establishment, yet molecular mechanisms governing uterine receptivity and embryo-maternal interactions remain poorly understood. This study investigates the expression and localization of Fibroblast Growth Factor 7 (FGF7) and its receptor FGFR2IIIb in the left (LUH) and right (RUH) uterine horns of pregnant dromedary camels. We examined endometrial, and conceptus tissues collected on Days 8, 10, and 12 post-ovulation (PO). Results revealed that FGF7 mRNA expression in the LUH progressively increased from Day 8, peaking on Day 12, whereas no significant changes were observed in the RUH. Immunohistochemical analysis confirmed higher FGF7 protein intensity in LUH, particularly on Day 12, with predominant localization in the glandular epithelium and blood vessels. However, FGFR2IIIb mRNA and protein expression remained stable on Days 8 and 10 but significantly increased on Day 12 in both uterine horns, with higher levels in the LUH. In conceptuses, FGF7 mRNA was not detected at any pregnancy stages, yet its protein was present on Day 12. Conversely, FGFR2IIIb mRNA and protein expressions were undetectable on Day 8 but showed gradual upregulation from Day 10, peaking on Day 12. In conclusion, the preferential upregulation of FGF7 and its receptor FGFR2IIIb in the LUH may have a crucial role in the higher implantation success in this uterine horn. These findings provide novel insights into the molecular regulation in both uterine horns during early pregnancy in dromedary camels and may aid in developing strategies to enhance reproductive efficiency in this species.