Fig. 8

a The summary of oogenesis in different models shows the step and the stage where the noradrenergic input is required to maintain oocyte quiescence. Oocyte quiescence is maintained by OA. Quiescent oocytes are awakened by sperm in C. elegans and by nutrients in D. melanogaster. In zebrafish, NE would be overridden by nutrients, which serve as a signal of PFA. Under starvation conditions, early stage vitellogenic oocytes are subjected to degeneration in D. melanogaster and zebrafish. b For flies and zebrafish, oogenesis is tightly regulated by availability of food. When nutrients are completely deprived (0), oogenesis does not initiate due to lack of building blocks and energy. When nutrients are abundant (high), oogenesis progresses in full speed overriding any inhibitory signals such as NE/OA. When the nutrient level is insufficient for continuous oogenesis, NE/OA serves as a counterbalance signal to nutrients; oogenesis stops, and oocytes become quiescent waiting for the condition to be improved.