Interaction of different egg parts in determination of various body regions in Drosophila melanogaster.

When Drosophila melanogaster embryos were ligated at very early stages of nuclear multiplication (45-60 min after egg deposition) for the entire period of embryogenesis, egg fragments of variable sizes were able to continue development up to the hatching stage. These ligated embryos differentiated larval structures; anterior fragments formed larval head and posterior fragments formed larval abdominal structures. Ligation always prevented the differentiation of some of the intermediate larval bands whereas the terminal ones were always formed. Identical results were obtained when embryos (45-60 min after egg deposition) were temporarily ligated for only 5 min. However, puncturing with a fine glass needle immediately after temporary ligation through the ligated area could give rise to complete differentiation of all the bands. Since puncturing disrupted the barrier produced by ligation, we propose that interaction between anterior and posterior egg regions is necessary to allow complete development.