Submission Number: SCH-4-15-3

Abstract Number: 487

EXPRESSION AND LOCALIZATION OF VASCULAR ENDOTHELIAL GROWTH FACTOR (VEGF) AND BASIC FIBROBLAST GROWTH FACTOR (FGF2) DURING FINAL GROWTH OF BOVINE OVARIAN FOLLICLES.

D Schams* ¹, B Berisha ¹, M Kosmann ¹, W Amselgruber* ² and R Einspanier* ¹

Institute of Physiology, Technical University of Munich, Weihenstephaner Berg 5, D-85350 Freising-Weihenstephan, Germany ¹
Anatomy and Physiology, University of Hohenheim, D-70593 Stuttgart, Germany ²

Abstract:
Expression and localization of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (FGF2) during final growth of bovine ovarian follicles Locally produced growth factors may have important modulatory roles in final ovarian follicular growth. The aim of the study was to investigate the expression and localization of vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (FGF2) in bovine follicles during final growth. Ovaries were collected from a slaughterhouse within 10-20 min after exsanguination. A classification of follicles was performed according to the follicular fluid (FF) estradiol 17-(E) content into five classes (E <0.5; >0.5-5; >5-20; >20-180; >180 ng/ml).The corresponding size of follicles were in the range of 5-7, 8-10, 10-13, 12-4 and >14 mm respectively. Analysis of VEGF transcript by the RT-PCR showed that granulosa (GC) and theca tissue (TI) express predominantly the smallest isoforms (VEGF121 and VEGF165). VEGF mRNA expression in both tissues (TI and GC) and VEGF protein concentration in total follicular tissue increased significantly and correlated with developmental stage of follicular growth. The mRNA expression of the receptors VEGFR-1 and VEGFR-2 were very weak in GC without any regulating change during final follicular growth. In contrast, TI showed strong mRNA expression for both receptors during all follicle classes examined. VEGF protein concentrations in FF increased significantly and continuously to maximum levels in preovulatory follicles. As achieved by immunohistochemistry, VEGF protein was clearly localized in TI and GC of preovulatory follicles. FGF2 and FGFR mRNA expression in TI increased significantly during final growth of follicles. In contrast, the FGF2 and FGFR mRNA expression in GC was very weak and without any regulatory change during follicular growth. The histological observation revealed that FGF2 protein was localized in TI but not in GC of preovulatory follicles. Our results suggests that VEGF and FGF growth factor families are involved in the proliferation of capillaries that accompanies the selection of the preovulatory follicle resulting in an increased supply of nutrients and precursors, and therefore supporting growth of the dominant follicle. .

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This abstract is being presented at: 8:00 AM in session:
Growth Factors II