Histochemical differentiation of four species of the genus Trichinella from days 10-40 of their development in muscles of experimentally infected mice.

Differences in an infection of the muscle caused by larval T. pseudospiralis (from days 10-40 p.i.) and that caused by capsule-forming Trichinella larvae were disclosed with histochemical techniques. These were: An intense reaction of the modified sarcoplasm for neutral mucosubstances, and intense staining of spherical centres of re-differentiation in the sarcoplasm for tyrosine, activity of the acid phosphatase, a negative reaction for SS groups of proteins at the site of location of the parasite owing to the absence of a collagen-like substance deposited by capsule-forming Trichinella species. Alkaline phosphatase activity weak in a sarcoplasm infected with larval T. pseudospiralis, but intense in capsule-forming species suggesting a different, larval metabolism. The capsule of T. nativa which is produced later than that of T. spiralis and T.nelsoni, differs from these also histochemically in that it contains neutral polysaccharides on the surface of the outer capsule layer which stains for non-sulphonated, acid mucosubstances (hyaluronic acid). Inspection with the electron microscope disclosed a vacuolate substance containing glycoprotein, phospholipids, and displaying acid phosphatase activity. The substance was present in the vicinity of larvae of T. nativa occupying the space between the cuticle and the sarcoplasm. A slight, morphological difference between T. nelsoni and T. spiralis was observed in the more elongate shape of the capsule at days 30 and 40 p.o. Histochemical differences were in an oxidative reaction with aldehyde fuchsin (PAA AF, KMnO4 A F) showing an increased hypertrophy of the connective tissue surrounding muscle fibres infected with T. nelsoni.