Comparison of Growth of Trichomonas foetus and Trichomonas vaginalis in Chick Embryos. ∗

Nelson 1 first reported the cultivation of Trichomonas foetus in chick embryos after inoculations of 1 cc of a culture into the allantoic sac. The eggs were opened 3 to 4 days after inoculation. Allantoic fluid from the most heavily infected embryos was used to carry the protozoan through 14 subcultures. Later, Levine, Brandly, and Graham, 2 following the same procedure, carried T. foetus through 23 passages and found that 12-day embryos were better than others in an 8- to 16-day series tested. Hogue 3 inoculated T. foetus into the allantoic sac of developing chick embryos and allowed the embryos to hatch or die. In one of 4 chicks that hatched, the protozoa were found in the yolk sac, esophagus, intestines, gall bladder, and cloaca 2 days after hatching. The other 3 gave negative results on fecal examinations. In embryos that died after inoculation, the trichomonads were also found in the digestive tract, yolk, and gall bladder.

The present report concerns a comparison of the growth of bacteria-free cultures of Trichomonas foetus 4 and Trichomonas vaginalis 5 in chick embryos. Also, successful subculturing of T. vaginalis in chick embryos is recorded for the first time.

After a few preliminary trials, T. foetus was established in chick embryos and was carried through 14 passages in 78 days. The inoculations were made into the allantoic sac as described below for T. vaginalis. The organisms seemed to grow better after the first few subcultures. Seven- to 14-day-old embryos were employed and were inoculated with 0.1 cc to 0.4 cc of trichomonas-containing material. The small inoculum may explain the slight difficulty encountered in establishing the infection. The eggs were opened from 4 to 7 days following inoculation. Observations and experiences were essentially the same as those already reported by others. Examination of the different egg parts showed that the protozoa developed in the allantoic fluid or the amnionic fluid, but were not found in the egg white, the yolk sac, the actual embryo or its blood stream.