THE TRICHOMONADS 



83 



PARABASAL BODY 

 COSTA 



PARABASAL 



FILAMENT 



UNDULATING 

 MEMBRANE 



FREE FLAGELLUM 



CHROMATIC RING 



TRICHOMONAS 

 Fig. 6. Structures of Tyicliomonas. (Original) 



The costa consists of a series of discs 

 about 370 A thick and 490 A apart, em- 

 bedded in a matrix; it is attached to the 

 inner surface of the body wall by exten- 

 sions of the discs. The axostyle is lim- 

 ited by a double, corrugated membrane. 

 The chromatic ring is composed of a series 

 of rods about 640 A thick. The parabasal 

 body consists of a series of filaments about 

 190 A thick. The chromatic granules along 

 the costa, inside the axostyle and scattered 

 in the cytoplasm are irregular in shape and 

 vacuolated. The mitochondria are spher- 

 ical and contain a varying number of pro- 

 jections internally. 



Trichomonads are divided into sev- 

 eral genera on the basis of the number of 

 their anterior flagella. Ditrichomonas 

 has 2, Tritrichomonas has 3, Trichomonas 

 has 4, and Pentatrichonionas has 5. These 

 genera are closely related; Mehra, Levine 

 and Reber (1960), for example, found in a 

 column chromatographic study of the hy- 

 drolysates of Tritrichomonas foetus , T. 

 suis, Trichomonas gallinae, T. galli- 

 narum and T. buttreyi, that they are all 

 composed of the same amino acids but that 

 there are some differences in the amounts 



of each amino acid present in the different 

 species. 



Gabel (1954) established the genus 

 Paratrichomonas for P. marmotae from 

 the woodchuck and possibly T. batrachorum 

 from the frog. Paratrichomonas differs 

 from Tritrichomonas orincipally in having 

 a ring-shaped parabasal body. T. buttreyi 

 of the pig resembles it, but has 4 anterior 

 flagella. There does not seem to be suf- 

 ficient justification for accepting this genus, 

 at least at present. 



Morgan (1943, 1946) and Trussell (1947) 

 have given host-parasite lists of the trich- 

 omonad species. 



There are several species of tricho- 

 monads in domestic animals and man, but 

 the nomenclatorial status and host-parasite 

 relations of many of them are not yet clear. 

 They have been found in the cecum and 

 colon of practically every species of mam- 

 mal or bird that has been examined for 

 them, and they also occur in reptiles, am- 

 phibia, fish and many invertebrates. Those 

 in the termite gut are particularly well 

 known. Many of the cecal trichomonads 

 look alike, and cross-transmission studies 

 have shown that many of them can be easily 

 transmitted from one host species to an- 

 other. Some mammalian trichomonads 

 have even been transmitted successfully to 

 day-old chicks, altho they will not become 

 established in older birds. Further and 

 extensive studies are needed to establish 

 the correct names and host spectra of all 

 but a few trichomonads. 



Most trichomonads are non- pathogenic 

 commensals, but a few are important path- 

 ogens. None of the cecal trichomonads has 

 ever been proven to be pathogenic, altho 

 some people have thought that they were 

 because they were found in animals which 

 had enteritis or diarrhea. However, the 

 mere presence of an organism in a diseased 

 animal does not mean that the organism 

 caused the disease. The latter may have 

 set up conditions favorable to the organism's 

 growth and multiplication. This is espe- 

 cially true of the cecal trichomonads, which 

 flourish in a fluid or semi-fluid habitat. 



