The Laboratory Propagation of Spirometra mansonoides (Mueller, 1935) as an Experimental Tool. III. In vitro Cultivation of the Plerocercoid Larva in a Cell-Free Medium

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Abstract
Procercoids of S. mansonoides, removed from copepods, grow in a cell-free medium consisting of Mixture 199, calf serum, chick embryo extract, and antibiotics, to a length of 7 to 10 mm, in approximately 30 days, representing an increase in mass of several thousand percent. The cultures are grown in roller tubes, containing 7.5 ml of medium, at 37[degree]C, and medium is changed twice daily. Several thousands of procercoids are started in each tube, but require thinning as growth progresses. Initial growth is rapid, but slows down markedly after a length of 5 to 7 mm is attained. The bothria are defined during the 2d week, and the worms move constantly with a peristaltic movement. The cultures are axenic. Such culture-reared sparganules are infective to cats, producing normal adult tapeworms. A 2d generation of plerocercoids, descended from these worms, have again been grown in culture. The necessary appointments of the laboratory, and manipulation of cultures are described in detail. The worms are washed and transferred to new tubes once a week to get rid of precipitates. Different worms vary greatly in growth rate. Heads of large spargana, removed from experimental mice, have been maintained for a year in culture, but fail to grow. The formation of precipitates in the bothria and around the neck of the worms suggests that these regions must be intensely reactive with the culture medium.