Mechanisms Regulating Blood Vessel Growth in the Early Bovine Placenta
Open Access
- Author:
- Hayes, Emily
- Area of Honors:
- Animal Sciences
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- Troy Ott, Thesis Supervisor
Chad Daniel Dechow, Thesis Honors Advisor
Francisco Javier Diaz, Faculty Reader - Keywords:
- Hypoxia-inducible factor-1
HIF1a
angiogenesis
bovine
uterine endometrium - Abstract:
- The U.S. dairy industry is among the highest milk-producing industries in the world. Improved fertility and healthy pregnancies are needed to keep up with this demand. A key aspect of pregnancy includes implantation and placentation, which involves attachment of the fetal membrane to the maternal endometrium and extensive angiogenesis. However, the process of bovine placental angiogenesis is poorly understood. Hypoxia-inducible factor-1 (HIF1a) induces blood vessel growth to ensure an adequate blood supply to hypoxic tissues via angiogenesis. We hypothesize that the presence of a conceptus will increase endometrial HIF1a expression, thus leading to increased placental angiogenesis. We assessed this hypothesis by inseminating dairy heifers and collecting uterine tissue samples on days 17 and 20 post-insemination. These samples were used to determine HIF1a protein localization within the tissue via immunofluorescence analysis and mRNA quantification of HIF1a, vascular endothelial growth factor A (VEGFA), and angiopoietin-like 4 (ANGPT4) via RT-qPCR analysis. Results were compared to uterine samples of estrus-synchronized dairy heifers collected on day 17 post-estrus. Immunofluorescence analysis showed stronger labeling of HIF1a in various stroma and intracellular spaces central to glands and blood vessels and little to no labeling in glands or luminal epithelium. RT-qPCR analysis found a low detectable amount of HIF1a mRNA in samples across the three groups. However, more abundant mRNA expression was detected for VEGFA and ANGPT4. Furthermore, VEGFA mRNA expression remained relatively consistent across all groups, while ANGPT4 mRNA expression was lower in the pregnant groups when compared to the cyclic group. Further work is needed to determine the effects of early pregnancy on HIF1a in the uterine endometrium.