The in vitro cultivation of Hymenolepis diminuta: The culture of 6-day-old worms removed from the rat

Abstract

Six-day-old Hymenolepis diminuta from the rat was cultivated in a modification of the diphasic medium described by Schiller (1965). The modified medium contained defibrinated horse blood. In this medium worms increased in length, segmented, developed to maturity and produced preonchospheres. A diphasic serum-agar medium without blood was developed which contained horse serum, yeast and liver extracts in the solid agar and supernatant fluid phases. In this medium worms grew as well as in Schiller's medium containing horse blood and produced onchospheres, but the worms tended to knot and fracture in both media. Attempts to induce worms to migrate to lie beneath the solid phase of the diphasic serum-agar medium failed, consequently the volumes of the solid and fluid phases were modified. Worms migrated below the agar of the modified medium (14 ml of serum-agar, 22 ml of fluid overlay) and displayed reduced knotting compared with those remaining in the supernatant fluid. However, the immature anterior segments of worms which migrated, as with those that did not migrate, deteriorated and fractured. Neither increasing the oxygen in the medium nor culturing worms in a monophasic medium in tubes prevented the deterioration of the immature segments, but worms grown in a medium preincubated in air (i. e. with more oxygen) had a higher dry weight than those cultivated in the same medium preincubated in 5% CO2 in N2. The replacement of horse serum in the monophasic medium with defibrinated horse blood did not prevent the degeneration of the immature segments.