Strongyloides ratti: migration study of third-stage larvae in rats by whole-body autoradiography after 35S-methionine labeling
Koga, M.; Ning, A.; Tada, I.
Journal of Parasitology 85(3): 405-409
1999
ISSN/ISBN: 0022-3395 PMID: 10386429 Document Number: 508512
To study the migration pathway of Strongyloides ratti, 16 Wistar rats were inoculated subcutaneously with 5000 35S-labelled infective larvae and killed at 10, 15, 20, 25, 30, 40 and 50 h pi. Prior to inoculation, the specific radioactivity level was assessed in the labelled larvae using a scintillation counter. Frozen rat specimens were sectioned at 50 micro m and the sections were freeze-dried and mounted on X-ray film in darkness. The labelled larvae appeared as dark spots on the film after 14 days of exposure. The larvae remained at the inoculation site (lower abdomen) until 10 h pi. Some larvae were found in the head and others were present sporadically in the skin, liver and lungs at 15 h pi. After 20 and 25 h, most larvae had accumulated in the head region. Many larvae appeared in the cranial and nasal cavities; however, none was found in any other organs or tissues. At 30 h pi, most larvae had begun to accumulate in the ethmoid region. At 40 and 50 h pi, some larvae were present in the ethmoid region but most had reached the small intestine. The results suggest that the larvae migrate directly to the nasofrontal region via the subcutis, rather than migrating to the head via the viscera, ascending vessels or foramen occipital magnum.