Fig. 7.

Fig. 7. Model of germline-somatic-immune cell axis in healthy ovary and during ovarian failure.

Schematic depicts the signals and cellular players in (A and B) healthy ovary. Bmp15 from the oocyte signals to promote somatic follicle fates and survival such that the balance of Activins (Inhb) and Inhibins (Inha) prevents release of Csf1a and Il34 from pre-follicle cells and MAFCs, which express activin receptors, thereby blocking activation or expansion of macrophages. (C and D) During ovarian failure caused by loss of Bmp15, this balance tips to favor Inhibin a causing elevated Il34, and MAFCs to release Csf1a. Together, elevated Il34 and Csf1a trigger macrophage activation and activation of programs that regulate ovary-to-testis remodeling and sex reversal in zebrafish. (B) and (C) Enlarged views of regions boxed in (A) and (D).