THE MORPHOLOGY AND DEVELOPMENT OF THE SHEEP NEMATODE, STRONGYLOIDES PAPILLOSUS (WEDL, 1856)

Abstract

In studying the morphology and development of Strongyloides papillosus it has been shown that four molts occur during the development of the free-living sexual adults, two molts in the formation of the infective larvae, and two molts in the development of the parasitic adults from the infective larvae. The last two occur in the body of the host, one in the lungs and the other in the intestine. The time required by the eggs to hatch and the larvae to develop to either the infective larvae or the free-living adults varies with temperature; at 27 °C. it is 6 hr. and 28 hr., respectively. The so-called "spears" in the oesophagus of the free-living adults were found to be the cuticularized tubular endings of the rays of the oesophageal lumen. The head in the free-living adults bears two well developed lips and four papillae, while in parasitic adults it has four lips and four papillae. The tail of the free-living male bears two pairs of preanal and two pairs of postanal papillae. No males were found in the parasitic generation, while parasitic females were found only in the intestine of experimental animals.