Quantitative vascularity of antral follicle in Bos indicus using Factor VIII immunolocalization

To quantify vascularity of antral follicles in Bos indicus using Factor VIII immunohistochemistry in order to investigate the relationship between follicular size, health status and vascularity, bovine ovaries were obtained on d 6 of the estrous cycle from mature B. indicus (n=8) after a synchronized estrus with PGF2α analogue. The ovaries were perfused and used for immunofluorescence detection of Factor VIII (a marker of endothelial cells). Follicles were classified by size (small, medium, and large) and by morphology as healthy and atretic follicle. Quantitative analysis was determined by the aid of image analysis. Factor VIII binding was localized exclusively in the thecal layer and stroma of the antral follicles, but was not found in the granulosa layer. For all follicles evaluated, capillary area density (CAD) and capillary number density (CND) were greater (P<0.05) in the small and medium follicles compared to the large follicle. However, area per capillary (APC) was greatest in small follicles compared with large follicles but was not different when compared with medium follicles. The average CAD, CND, and APC of the healthy follicles were greater (P<0.05) than that of the atretic follicles. The CAD was also greater (P<0.05) in the healthy follicle (small, medium, and large) compared to the atretic follicle (small, medium, and large). CND was greatest (P<0.05) in theca layer of healthy small follicle and was lowest in atretic large follicle. APC was least (P<0.05) in theca layer of the atretic large follicle. These results demonstrated that immunofluorescence detection of Factor VIII can be used as a reliable marker of endothelium to quantify vascularity of antral follicles in B. indicus. There was no interaction between follicular health and size on vascularity of antral follicle. A decline in vascularity was observed in atretic follicle and large size of atretic follicle in B. indicus.