Metabolic indices for evaluating the in vitro maintenance of Hymenolepis diminuta in the presence and absence of various additives.

An in vitro maintenance system for H. diminuta was devised by modifying the cultivation procedure of Schiller (1965). In this diphasic maintenance system, tissue culture medium (Triple Eagle's or NCTC-135) was used, in lieu of whole blood, as the 30% supplement to the agar phase. This provides a more defined system suitable for studying the effects of various additives. Morphological criteria were established which aided in assessing the efficacy of media used for the maintenance of 6- and 8-day-old H. diminuta. When successfully maintained, worms exhibited an intact scolex and neck region, undulatory movements along the strobila as well as integumentary and strobilar integrity. A more sensitive method for evaluating the maintenance of 8-day-old worms employed metabolic indices. Wet weight, protein and glycogen levels for 8-day-old H. diminuta served as base-line data allowing estimation of protein and glycogen contents of each worm prior to maintenance. Following maintenance, ratio of final to initial protein and final to initial glycogen levels (metabolic indices). A metabolic index approaching or exceeding unity suggested a reasonably intact metabolism. The addition of sodium taurocholate to the maintenance media appeared beneficial to the worms by prolonging the retention of normal signs. A combination of additives, taurocholate-nucleosides-lipids, improved the maintenance of H. diminuta for periods exceeding 24 hr as determined by observational criteria and metabolic indices. However, addition of a lipid mixture, or a lipid mixture prepared with a low concentration of taurocholate was not beneficial over a 24 hr period. The maintenance system, observational criteria, base-line data and metabolic indices should be useful for future in vitro studies requiring long-term incubation.