Effect of ecdysterone contact period on development of wing disks of the fleshfly, Sarcophaga peregrina, in vitro

The ecdysterone contact period required for pupal development of Sarcophaga wing disks was studied in vitro. When the disks were cultured in a medium with 1 × 10^?6 M ecdysterone for about 21 hr, evagination of wing disks occurred independent of a later transfer into a hormone-free medium. The contact period required for wing evagination was dependent on the concentration of ecdysterone.When the disks cultured in the ecdysterone-containing medium were subjected to an intervening ecdysterone-free condition, evagination of the wing occurred if the period of the hormone contact before and after the ecdysterone-free period totalled a certain length. The total period required for wing evagination was altered both by the duration of the intervening hormone-free culture and duration of the first culture with ecdysterone.The morphogenetic effect of ecdysterone is discussed in relation to RNA synthesis in vitro.