Some Preliminary Observations on the Development of Echinococcus in Vitro

A variety of media and techniques has been employed in attempts to grow various stages of Echinococcus in vitro. Whole, intact Echinococcus multilocularis cysts and undifferentiated cystic material proliferate readily in chemically defined media, but except for a single occurrence, no scoleces developed within the new vesicles. Scoleces can be induced to develop either toward the tapeworm stage or the vesicular larval stage by altering the medium. In the first case, the scoleces increase in size, the excretory system becomes prominent, and segmentation is advanced; gonads have not developed in any medium yet employed. Scoleces may vesiculate in several ways; ultimately, they become vacuolated, the suckers are absorbed, the hooks shed, and a thin, laminated membrane is laid down. Local internal thickenings probably represent secondary brood capsules or scoleces.