Moncol D J, Triantaphyllou A C
J Parasitol. 1978 Apr;64(2):220-5.
Among the progeny of parasitic females of Strongyloides ransomi, ransomi, males did not appear in significant numbers until the 7th week of infection in cases of simple infection, and until the 3rd week of infection in cases of multiple infection. The appearance of males was attributed to the effect of host immunity, the physiological ageing of the parasitic females, or both. Type of culture substrate and other cultural conditions did not influence the percent of larvae developing into males. Sex of larvae was determined prior to hatching, probably during oogenesis or embryogenesis. Culture conditions influenced the direction of development of female larvae. An initial pH below 5.9 or above 7.2 favored differentiation of larvae into infective larvae, whereas, intermediate initial pH levels favored development of free-living females. Baby pig substrate, autoclaved substrate, and substrate washed free of soluble chemicals (adverse cultural conditions) promoted differentiation toward infective larvae. Adult pig substrate, nonautoclaved substrate and unwashed substrate promoted differentiation toward free-living females. In general, adverse conditions inside the host and favor an indirect life cycle.
在兰氏类圆线虫寄生雌虫的子代中，单纯感染情况下，雄虫直到感染第7周才大量出现；多重感染情况下，直到感染第3周才大量出现。雄虫的出现归因于宿主免疫效应、寄生雌虫的生理老化，或两者皆有。培养底物类型和其他培养条件不影响发育为雄虫的幼虫百分比。幼虫性别在孵化前确定，可能在卵子发生或胚胎发生期间。培养条件影响雌虫幼虫的发育方向。初始pH低于5.9或高于7.2有利于幼虫分化为感染性幼虫，而中等初始pH水平有利于自由生活雌虫的发育。仔猪底物、高压灭菌底物和洗去可溶性化学物质的底物（不利培养条件）促进向感染性幼虫的分化。成年猪底物、未高压灭菌底物和未洗涤底物促进向自由生活雌虫的分化。一般来说，宿主体内的不利条件有利于间接生命周期。
