Sommerville R I, Murphy C R
J Parasitol. 1983 Apr;69(2):368-71.
Exposure of Haemonchus contortus infective larvae to carbon dioxide under specific conditions is believed to activate a succession of events that ultimately control both exsheathment and subsequent development to the fourth stage. Rarely at pH 6, but always at pH 2, worms fail to exsheath yet develop to the fourth stage surrounded by cuticles two and three. Failure to exsheath is probably a consequence of inactive enzymes in exsheathing fluid, because exposure to EDTA, which inactivates exsheathing fluid, reduced exsheathment and yielded sheathed fourth-stage worms. Although exsheathment is blocked at pH 2, CO2 can activate the receptor for exsheathment as readily at pH 2 as at pH 6. Therefore the hypothesis that an early common pathway controls both exsheathment and development is not invalidated.
在特定条件下，将捻转血矛线虫感染性幼虫暴露于二氧化碳中，据信会引发一系列事件，最终控制脱鞘及随后发育至第四阶段。在pH 6时很少出现，但在pH 2时总是如此，虫体无法脱鞘，但能发育至被第二和第三层角质层包围的第四阶段。无法脱鞘可能是由于脱鞘液中酶失活所致，因为暴露于使脱鞘液失活的乙二胺四乙酸（EDTA）会减少脱鞘，并产生带鞘的第四阶段虫体。尽管在pH 2时脱鞘受阻，但二氧化碳在pH 2时与在pH 6时一样能轻易激活脱鞘受体。因此，早期共同途径控制脱鞘和发育的假说并未被推翻。
