On the Tissue Phase of the Life Cycle of the Fowl Nematode Ascaridia galli (Schrank)

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Abstract
A study was made on 5 groups of chickens of about 25 each inoculated with infective eggs of A. galli to determine details of the tissue phase of the life cycle of thi3 parasite. Larvae free in the intestinal lumen (lumen-larvae) were removed by flushing with warm water under pressure. Collection of larvae partially imbedded in the intestinal mucosa (tissue phase) was accomplished by application, apparently for the first time to a problem of this kind, of a mass digestion apparatus. Whereas the tissue phase was thought to be from the 10th to the 17th day of parasitism, the present studies show that it may begin on the 1st day and that it may occur as late as the 26th day of parasitism. The great majority of the young Ascaridia. however, appear to make their sojourn in the intestinal mucosa from about the 8th to the 17th day of parasitism. No appreciable differences in the growth rates of the larvae recovered from the lumen and those isolated from the intestinal mucosa (mucosa-larvae) occurred until the 14th day, after which the lumen worms appeared to grow at normal rates, while the mucosa-larvae showed little or no growth. Of the 4 moults characteristic of this nematode, the , 1st occurs in the egg, the 2d moult of the lumen-larv^s.- in the 6th-to 8th-day period, the 3d during the 14th and 15th days, and the 4th in the 18th to 22d-day period. Moulting of mucosa-larvae was irregularly retarded. Evidences of the 2d moult occurred from the 8th to the 17th day; and completion of the 3d moult was not noted in mucosa-larvae. Failure of the 14-to 26 day mucosa-larvae of A. galli to grow at rates comparable to those of the lumen-larvae of these ages is attributed to retarded moulting of larvae in the tissue phase. Mucosa-larvae appear not to be developed for effective feeding or major growth. Diminutive larvae occurring.among normal sized larvae in lumen flushings doubtless are mucosa-larvae which have been swept from their mucosal moorings in the flushing process, or have just re-entered the lumen. Mucosa-larvae as well as lumen-larvae appeared to be somewhat restricted in number by increased natural resistance of chickens parasitized when 60 days old as compared with those from younger fowls of respective ages 23 and 38 days.
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