develops from oocyte stage S12C oocyte stage S13 oocyte Oocyte during stage 13 of oogenesis. It has reached its maximum volume and is completely sealed by the vitelline membrane (King, 1970). Its nuclear envelope starts to break down and the chromosomes move to the metaphase plate of meiosis I and arrest (Mahowald and Kambysellis, 1980) until fertilization (Puro and Nokkala, 1977). FBbt:00005278 fly_anatomy.ontology