Immunostaining of Gonadotropin Receptors in Ovarian Follicles of <i>Bos Indicus</i> Cows With High and Low Antral Follicle Count

This study aimed to assess differences in the immunostaining intensity of follicle-stimulating hormone receptor (FSHr) and leutenizing hormone receptor (LHr) receptors in the ovarian follicles of Bos indicus cows with high or low antral follicle counts (AFCs). Ovaries from cyclic Nelore cows (N = 20) were obtained from a local slaughterhouse and classified based on AFC (≥ 3 mm) into high- (≥ 30 follicles, N = 10) and low- (≤ 15 follicles, N = 10) AFC groups. Immunohistochemical studies were performed for FSHr and LHr. Immunostaining intensity was measured using ImageJ software with the IHC Profiler plugin, and pixel intensity was measured on a scale of 0 (darkest) to 255 (lightest). An interaction was observed between the AFC group and follicular developmental stage for FSHr immunostaining intensity, with preantral follicles from the low-AFC group showing highest immunostaining intensity (p < 0.0001). The FSHr immunostaining intensity of antral follicles from the low-AFC group was higher than that of the high-AFC group (p = 0.03). LHr immunostaining intensity also was higher in the low-AFC group than in the high-AFC group (p = 0.002). These findings suggest that ovarian follicle characteristics of low-AFC cows have distinct characteristics that could affect their response to reproductive treatments.