Differentiation strobilar

With the exception of a few species with progenetic plerocercoids (e.g. Schistocephalus) it is only within the definitive host that cestode tissue develops in a strobilar direction, and it is self-evident that strobilar differentiation must be induced by factors present in the intestinal environment. Clearly, any number of known parameters of the intestine (Fig. 3.1, p. 37)... 

Contrasting results have also been obtained with different species of Mesocestoides. In M. corti, the chief factors inducing strobilar differentiation in vitro appear to be anaerobic conditions (Fig. 10.12, p. 280) and a pH greater than 7.4 (606,607,806). Yet in M. lineatus, the presence of trypsin in the culture media is required for sexual differentiation (382). These phenomena are discussed in further detail in Chapter 10. Whatever the nature of the stimulus which initiates sexual differentiation, there is now strong experimental evidence that it operates via the neurosecretory system. It was speculated, many years ago, that in E. granulosus, the contact stimulus operated via a neurosecretion which in turn induced the release of a strobilisation organiser (796). 

Fig. 10.4. Potential development of a protoscolex of Echinococcus granulosus or E. multilocularis in different habitats. 1, In the dog gut, the scolex evaginates, the organism attaches to the mucosa, differentiates in a strobilar direction and develops into an adult tapeworm. 2, In vivo, if a hydatid cyst bursts or leaks (as during a surgical operation) each protoscolex can differentiate in a cystic direction and form a (secondary) hydatid cyst. (After Smyth, 1987b.)...

IN VITRO DIFFERENTIATION OF SEXUAL ( = STROBILAR) STAGES Echinococcus granulosus... 

Smyth, J. D. Barrett, N. J. (1979). Echinococcus multilocularis further observations on strobilar differentiation in vitro. Revista Iberica de Parasitologia, 39 39-53. 

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