BMP4 and obesity due to melanocortin 4 receptor deficiency: As obesity led to an increase in the number of atretic follicles, we wondered if this increase was induced by the abnormal expressions of the genes BMP4, GDF9, or LHX8 that play key roles during ovarian follicular development (Fu et al., 2017; Liu et al., 2017; Stocker et al., 2020).