Morphogenesis of the Parasitic Stages of Ostertagia ostertagi, a Nematode Parasite in Cattle

Abstract

Morphological features of value in the identification of the parasitic larval stages and young adult stage of O. ostertagi are described and figured. Some of the cephalic, stomatal and esophageal structures observed in the 3d- and 4th-stage larvae and young adult have not previously been reported or correctly interpreted. Given also are the apparent time intervals which this nematode sp. requires to progress from stage to stage in its development in the cattle host.