| Popis: |
The morphogenesis of Stephanurus dentatus larvae collected from swine 1 to 32 days following oral inoculation was studied and the results compared with those from previous studies done in vitro and in an abnormal host, the guinea pig. The morphology described previously for in vitrogrown larvae was sufficient to identify the phase of development of larvae recovered from swine. The third molt occurred 3 to 6 days after infection. Larvae could be separated by sex in an early phase of fourth stage, as early as 6 days after infection, on the basis of the position of the genital primordium and the presence of the spicular primordia in males. The development of the stoma, excretory gland cells, and the esophagus was found to be related to the migration of fourth-stage larvae to the liver. From 1 to 9 days after infection, large numbers of larvae were found only in mesenteric lymph nodes and none in the liver. Both recovery and morphological data strongly suggest that a migration of larvae from mesenteric lymph nodes to the liver occurred 10 to 32 days after infection. Development of the reproductive organs and the greatest increase in size of the larvae occurred in the liver. The fourth molt occurred in the liver from 24 to 32 days after infection. Previously the morphogenesis of immature parasitic stages of the swine kidney worm, Stephanurus dentatus, has been described only from specimens grown in guinea pigs (Clunies Ross and Kauzal, 1932) and in vitro (Douvres, Tromba, and Doran, 1966). The present report describes the morphogenesis of larval stages in the normal host and compares the findings with those from the studies in guinea pigs and in vitro. In the course of the study, previously unknown details of the life cycle of S. dentatus were observed. MATERIALS AND METHODS |
