Structure of Trichomonas vaginalis Donne

The structure of Trichomonas vaginalis is described from direct smears of vaginal secretions and from axenic cultures. The employment of protargol stain and observations of living organisms with the aid of phase contrast clarified some of the hitherto inadequately understood morphological details and relationships. The former method was particularly helpful in revealing the structure of the parabasal apparatus and of the axostylar capitulum. The latter allowed a study of the motion and of the formation of pseudopodia; it was also found superior for the analysis of the distribution of cytoplasmic inclusions such as the paraxostylar and paracostal granules. The discussion includes a comparison of the urogenital trichomonad of man with the two closely related species, Trichomonas tenax and T. gallinae. Trichomonas vaginalis Donne is a protozoan parasite commonly found in the urogenital tract of men and women. As far as is known this flagellate is limited in its distribution to human hosts. It may be stated without fear of exaggeration that only a few parasitic protozoa have been the subject of more extensive morphological and physiological study than the trichomonad in question. Yet there seems to be no account of the structure of this species based on observations of living material with the aid of phase contrast or of preparations stained with protargol. Among the techniques employed previously in the studies of T. vaginalis the iron-hematoxylin method of staining gave the most satisfactory results. Through the use of this technique many workers were able to describe accurately numerous morphological details of the flagellate. Of the more recent investigators, Wenrich (1931, 1939, 1944, 1947), Powell (1936), and Hawes (1947) contributed most significantly to the understanding of the structure of T. vaginalis. Despite the great interest in this trichomonad there appear to be only two apparently preliminary reports (Inoki et al., 1959, 1960) of its fine structure, Received for publication 1 April 1964. * This investigation was supported by Research Grant AI-00742 from the National Institute of Allergy and Infectious Diseases, Public Health Service. and there can be no question of the pressing need for further electron microscopic studies of this and all the other trichomonad species. The present report is designed to supplement and complement the previous morphological accounts of T. vaginalis by describing numerous strains of this species on the basis of observations of living material with the aid of phase contrast and of fixed preparations stained not only with iron hematoxylin (or hematein), but also with protargol. Also, some mensural considerations have been included which may aid further in the establishment of the morphological identity of the urogenital trichomonad