PARENT SESSION
PLATFORM SESSION 9: VASCULAR AND INTRACELLULAR SIGNALS IN CORPUS LUTEUM
Chair: Davis, John¹, ¹
Co-chair: Valdezk, Kelli¹, ¹
Grand Ballroom V
2:00 PM-4:00 PM

(209) EXPRESSION AND LOCALIZATION OF VASCULAR ENDOTHELIAL GROWTH FACTOR AND ANGIOPOIETIN -1 AND THEIR RECEPTORS FLT-1, FLK-1, AND TIE-2 IN BOVINE OVARIES DURING FOLLICULAR AND LUTEAL DEVELOPMENT.

Greenaway, James¹, LaMarre, Jonathan¹, Petrik, Jim¹, ¹ Dept Biomedical Sciences, Guelph, CA

ABSTRACT- Tissue and temporal specific expression of angiogenic growth factors are essential for normal follicle and corpus luteum formation in the ovary. Without this complex sequence of events normal mammalian pregnancy would not be possible. This study focused on expression and localization of the angiogenic factors vascular endothelial growth factor (VEGF) and angiopoietin -1 (ANG-1) and their receptors FLT-1, FLK-1 and TIE-2. Bovine ovaries were collected at slaughter and the follicles were sorted based on size into small (<0.5cm), medium (0.5-1.0cm) and large (>1.0cm) groups. Tissues were subjected to immunohistochemistry and western blot analysis. Immunohistochemistry localized VEGF in both granulosa and theca cells of small, medium and large follicles and luteinized cells of the corpus luteum. Western analysis illustrated an increase in VEGF expression towards late follicular development. The first of the two VEGF receptors, FLK-1, was not expressed to a significant extent in small follicles except in peripheral capillary beds. Distribution of FLK-1 was seen in the granulosa, theca and blood vessels in the medium and large follicles. FLK-1 in the corpus luteum was restricted to endothelial cells of blood vessels. The type 2 VEGF receptor, FLT-1 was present in both granulosa and theca of all follicles and the luteinized cells of the corpus luteum. Western immunoblot of follicular fluid displayed an increase in expression of FLT-1 from small to large follicles with immunohistochemistry displaying granulosa staining more intensely than theca cells. Preliminary data localized ANG-1 exclusively to the granulosa cells of follicles at all stages of development, but no staining was apparent in the corpus luteum. The distribution of TIE-2 in all stages of follicular and corpus luteum development was localized to the ovarian vasculature. TIE-2 expression increased from small follicles to corpus luteum as seen by Western blotting. Elucidation of the mechanisms of angiogenesis in bovine follicular and luteal development will have significant implications in reproductive management of these domestic species.

KEY WORDS: Follicular Development, Angiogenesis, Ovary, Bovine