Expression of VEGF165 and VEGF165b during ovarian follicular development

To investigate the role of vascular endothelial growth factor (VEGF)165a, VEGF165b, and VEGF receptor (VEGFR) in the development of bovine follicles. We cultured follicular cells that were collected from small, medium, and large sized bovine follicles with estrogen and measured the expression of VEGF, VEGFR2 and VEGF165b by Western blot analysis and immunofluorescence. The expression of VEGF165 increased in all follicle sizes and the expression of VEGF165b was increased in the small and large follicles after culturing in an estrogen containing medium. The expression of VEGFR2 was increased in the medium and large follicles after culturing with estrogen for 96 h. VEGF165 was activated at 100 ng/mL estrogen in the large follicles for 96 h. In addition, VEGFR2 was upregulated in the medium and large follicles after treated with 100 ng/mL estrogen for 96 h. This evidence suggests that the expression of VEGF165 and VEGFR is associated with estrogen stimulation during the development of bovine follicles and in an autocrine or paracrine manner. This reveals an advantage during oocyte maturation in vitro.