Abstract
Two human endodermal sinus tumours (yolk sac tumours) were transplanted successfully into nude mice. The transplanted tumours maintained not only morphological characters, such as Schiller-Duval bodies, but also the ability to synthesise alpha-fetoprotein, lactic dehydrogenase 1, liver and bone type alkaline phosphatase, and some human serum proteins. Since these tumours produced lactic dehydrogenase 1 but not the other four isozymes of lactic dehydrogenase, this isozyme, like alpha-fetoprotein, seems to be a good marker for the diagnosis and management of cases of endodermal sinus tumour. One of the two tumours produced another fetal antigen or carcinoembryonic antigen in addition to alpha-fetoprotein. These two endodermal sinus tumours, with their various markers in nude mice, will be useful in studies on diagnostic markers.