[The role of the prothoracic glands in the production of ecdysone during the last larval instar of Locusta migratoria L].

Tritiated cholesterol is rapidly converted to labelled ecdysone in vitro by prothoracic glands from last instar larvae of Locusta at the time of the maximum endogenous hormone increase of the insects. Glands from larvae with low hormone content or fat body fragments do not make similar conversions.