Hormone-mediated formation of the endocytic complex in mosquito oocytes

The developmental events leading to oocyte competence to internalize proteins, and the hormonal control of these events in the mosquito Aedes aegypti have been studied. The oocytes of newly eclosed females have an undifferentiated cortex. During previtellogenic development, a highly specialized endocytic complex, consisting of numerous coated vesicles and uncoated endosomes, microvilli, and, presumably, vitellogenin receptors, forms in the oocyte cortex. Morphometric analysis and probes with a protein tracer, horseradish peroxidase, have shown that only the oocytes with developed endocytic complexes are competent for protein uptake. In vivo experiments have demonstrated that the formation of the endocytic complex is controlled by juvenile hormone from the corpora allata. This developmental event was blocked by ablation of corpora allata at eclosion, but it was restored by either implantation of corpora allata into allatectomized female or the application of juvenile hormone III.