▁life ▁cycle ▁of ▁this ▁insect ▁has ▁four ▁stages : ▁fert il ized ▁egg , ▁lar va , ▁pup a , ▁and ▁adult . ▁ ▁Emb ry ogen esis ▁in ▁D ros oph ila ▁has ▁been ▁extens ively ▁studied , ▁as ▁its ▁small ▁size , ▁short ▁generation ▁time , ▁and ▁large ▁bro od ▁size ▁makes ▁it ▁ideal ▁for ▁gen etic ▁studies . ▁It ▁is ▁also ▁unique ▁among ▁model ▁organ isms ▁in ▁that ▁cle av age ▁occurs ▁in ▁a ▁syn cy t ium . ▁ ▁During ▁o ogen esis , ▁cy top las mic ▁brid ges ▁called ▁" ring ▁can als " ▁connect ▁the ▁forming ▁o ocy te ▁to ▁nur se ▁cells . ▁N ut ri ents ▁and ▁development al ▁control ▁mole cules ▁move ▁from ▁the ▁nur se ▁cells ▁into ▁the ▁o ocy te . ▁In ▁the ▁figure ▁to ▁the ▁left , ▁the ▁forming ▁o ocy te ▁can ▁be ▁seen ▁to ▁be ▁covered ▁by ▁fol lic ular ▁support ▁cells . ▁ ▁After ▁fert il ization ▁of ▁the ▁o ocy te , ▁the ▁early ▁emb ry o ▁( or ▁syn cy t ial ▁emb ry o ) ▁under go es ▁rapid ▁DNA ▁rep lication ▁and ▁ 1 3 ▁nuclear ▁divisions ▁until ▁about ▁ 5 0 0 0 ▁to ▁ 6 0 0 0 ▁nuc lei ▁accum ulate ▁in ▁the ▁un separ ated ▁cy top las m ▁of ▁the ▁emb ry o . ▁By ▁the ▁end ▁of ▁the ▁e ighth ▁division , ▁most ▁nuc lei ▁have ▁migr ated ▁to ▁the ▁surface , ▁surrounding ▁the ▁y olk ▁sac