HISTOCHEMICAL-STUDIES OF SOME HYDROLYTIC ENZYMES IN THE GREGARINE DIGYALUM-OWENI (PROTOZOA, APICOMPLEXA)

Histochemical methods for non-specific esterases, acid phosphatase and alkaline phosphatase have been applied to the gregarine Digyalum owen i, parasitic in the rectal region of the intestine of some Littorina s pecies. Host intestines contain all three enzymes but only non-specifi c esterases are visualised in Digyalum, although no reactions occur in the nucleus and nucleolus or around the pouches of Digyalum. The appa rent lack of positive reactions for acid and alkaline phosphatase in D igyalum is perhaps due to the impermeability of the epicyte of Digyalu m; other possibilities are discussed.