Differentiation of pulsating regions in genital imaginal discs after culture in vivo (Drosophila melanogaster).

Abstract

AbstractAfter male genital discs of Drosophila melanogaster had been cultured for 8 to 19 days in the abdomens of adult female flies a number of them contained rhythmically pulsating regions. The percentage of discs which pulsated was dependent on the age of the donor larvae, the length of culture time, the presence or absence of ring glands and on the age of the host. The best conditions for the differentiation of pulsating discs were an old disc in a young host to which a ring gland from a mature larva was added.In normal development the genital disc after metamorphosis gives rise to the genital apparatus with morphologically differentiated ejaculatory duct, sperm pump and paragonia (soft parts) which contract rhythmically. In the cultured discs, however, the contractions are not accompanied by morphogenesis.The prospective fate of the pulsating region of a disc is mostly contracting soft parts of the genital apparatus, whereas the non‐contracting area forms mostly chitinous parts (anal plates, claspers, lateral plates). Other discs, e.g. leg discs and wing discs, which in normal development do not form involuntary muscles also do not contract after culture in vivo.It is concluded that the formation of pulsating regions represents a phase in the normal differention of genital discs. Some of the conditions which lead to pulsation are established early in the third instar within the cells which form the pulsating regions. Their full differentiation is influenced by hormones secreted by the ring gland.