The fine structure of peritrophic membranes of the blowfly, Calliphora erythrocephala, grown in vitro under different conditions.

The formation of peritrophic membranes (PM) in vitro was studied in a flow chamber in order to avoid the accumulation of metabolic substances during prolonged incubation. During the first 8 to 10 hr of incubation the production of PM was nearly constant—3·5 ± 1·4 mm PM/hr. After about 10 hr it decreased and stopped after about 35 hr. Between 1 and 8 hr after the beginning of incubation the width of the periodic crossband pattern reached or nearly reached the values found in PM which had formed in vivo; afterwards it decreased more and more. During the first 20 min of incubation a ‘disturbed zone’ of PM without any regular crossband pattern is formed.In the cardia of adult Calliphora erythrocephala there are three formation zones forming three PM of different fine structures. The fine structure of PM 1 to 3 formed in vitro during the first 6 to 8 hr of incubation in Leloup's medium 1, with an osmolarity of 340 mOsmol, a pH of 6·8, and a temperature of 27°C, does not differ from the PM grown in vivo. PM 1–3 grown in vitro in Tyrode's solution with added glutamine or in Leloup's medium with added β-ecdysone show a considerable increase in thickness and a disturbed formation of the electron dense layer of PM 1.