The stage-dependent resistance of the chorion to external chemical damage and its relationship to embryonic diapause in the annual fish,Nothobranchius guentheri

Summary The resistance of the embryonic chorion of the annual fishNothobranchius guentheri to chemical damage in vivo was investigated by the exposure of the embryos to protease. Embryos at stages 20, 33, and 43 were the most resistant to enzymatic action. These stages of development correspond respectively to the stages at which diapause I, diapause II, and delayed hatching may occur. The magnitude of the resistance was further enhanced when diapause was induced prior to the treatment.