Functional morphology and histochemistry of structural proteins of the genital cone of Ostertagia ostertagi, with a comparison of the genital cones of other Ostertagia common in cattle in the United States.
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The structure, function, and histochemistry of the genital cone of Ostertagia ostertagi were studied and found to be similar to that previously reported for Cooperia punctata (1969). Distinct differences were found when the morphology of the genital cones of 2 species of Ostertagia in cattle in the United States were compared with the genital cone of 0. ostertagi. The genital cone of 0. ostertagi differs from that of 0. lyrata in having an unsclerotized accessory bursal membrane. The accessory bursal membrane of 0. lyrata is sclerotized dorsally and ventrally and connected by a sclerotized plate. The ventral plate of the genital cone of 0. ostertagi is sharply raised ventrally from the dorsoventral plate with a pair of long, ventral raylets on its posterior face as compared to the other 2 species. The dorsoventral plate is thick. Only 0. ostertagi has a prominent proconus. The accessory bursal membrane is delicate and at times barely visible on 0. bisonis. The ventral part of the genital cone is similar to that found in 0. lyrata but is much smaller. The split dorsoventral plate extends onto the dorsal part of the genital cone of 0. bisonis as compared to the other 2 species. The parts of the genital cones of the 3 species are illustrated. Homologous parts of the genital cones of the 3 species are correlated with one another and with the genital cones of Cooperia previously studied (Stringfellow, 1969, 1970). In recent publications (Stringfellow, 1969, 1970) I have determined the histochemical composition, function, and morphology of the sclerotized and cuticular parts of the genital cone of male Cooperia punctata and compared these observations concerning this species with other Cooperia species. This report relates similar observations on three species of Ostertagia that infect cattle in the United States. Each of these species has characters that readily distinguish it from the others, so much so that some workers have placed them in separate genera (Andreeva, 1957a). The histochemistry of the structural proteins, function, and morphology of the genital cone of Ostertagia ostertagi (Stiles, 1892) Ransom, 1907, is given herein, and the genital cones of 0. ostertagi, 0. lyrata Sjoberg, 1926, and 0. bisonis Chapin, 1925, are compared with one another as well as with previous findings on species of Cooperia. MATERIALS AND METHODS Functional morphology The genital cones of 13 0. ostertagi, 17 0. lyrata, and 20 0. bisonis of bovine origin were studied. Because of its possible synonymy with 0. bisonis Received for publication 17 September 1970. and the limited number of specimens available, Ostertagia orloffi was not studied (Becklund and Walker, 1967). Some specimens had been stored in a preservative of 92 parts 70% ethanol, 3 parts formalin, and 5 parts glycerine. This material was prepared for study from the caudal, lateral, dorsal, and ventral aspects, by using glycerine, lactophenol, and rosaniline-hydrochloride, respectively. All measurements given herein are in microns and were determined from both whole mount and sectioned worms with the aid of a calibrated ocular