The cultivation for development of Ascaris suum from the second-stage larvae(L₂) embryonated egg and the third-stage of rat-derived larvae(L₃) recovered from lung of rats were performed to use the screening test of anthelmintics in vitro. The preparations of larvae for cultivation were that the artificially-hatched L₂ incubated the embryonated eggs of Ascaris suum in 0.1% formalin solution at 25℃ for 28 days and the rat-derived larvae(L₃) recovered from the lung of rat infected with the embryonated eggs of Ascaris suum on 7 days after infection(DAI). The cultivation for development of Ascaris suum from the embryonated eggs(L₂) and the rat-derived larvae(L₃) for 14 days in RPMI medium 1640(with 5% bovine calf serum) were as follows :
1. The sizes of the liberated larvae(L₂) which were artificially hatched from embryonated eggs with glass beads(diameter 5mm) were 190-250㎛ on 1 days in culture(DIC). The second-stage larvae were molted into third-stage larvae(early L₃; 250-300㎛) and the features of these larvae were first observed such as cephalic cuticle, esophageal lumen and anus etc. on 5 DIC and the sizes of late third-stage larvae were 250-450㎛ on 10 DIC. The sizes of early fourth-stage larvae(L₄) were 500-700㎛ and the features of these larvae were more pronounced in internal organs on 15 DIC.
2. The sizes of third-stage larvae(L₃) recovered from the lung of rats were 1,340-1,370㎛ and the feartures of cephalic cuticle, esophageal lumen, intestine, rectum, anus were visualized by inverted microscope on 1 DIC. The fourth-stage larva(L₄) completed by third ecdysis were recognizable and sizes of early fourth-stage larvae were developed as 1,400-2,200㎛ on 5 DIC. The sizes of middle fourth-stage of larva were 1,900-2,300㎛ and the thickened epithelial rectum was observed on 10 DIC. The rectum and anus of late fourth-stage larva(L₄ 2,500-3,200㎛) had developed completely in RPMI medium 1640 on 15 DIC.
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