Optimum conditions for cultivation of Eimeria tenella in chicken embryos.

Abstract

Development of E. tenella in chicken embryos was observed under various conditions. The embryos, 10 days old, were inoculated with 103 sporozoites via the allantoic cavity, yolk sac, or chorioallantoic membrane (CAM) and incubated at 41°C. Oocysts were recovered only from the embryos inoculated into the allantoic cavity, where matured 1st generation schizonts were found at 48 hours after inoculation, 2nd generation schizonts at 72 hours, and gametes and oocysts at 144 hours. Many oocysts were located in the CAM and in the urate deposits, and a few in the allantoic fluid. Similar oocyst yields were observed with embryos on days 7 and 8 after inoculation, between which periods there was no appreciable difference in oocyst sporulation rate. The mortaIities did not differ significantly among embryos inoculated between 8 and 12 days of age, while the lowest oocyst yield was obtained from the embryos inocu1ated at 8 days of age. The mortality increased with increment of the inoculum size between 100 and 100, 000, and the oocyst yield increased proportionally to logarithm of the dose from 63 to 10, 000. It is obvious from the results that the oocysts were efficiently harvested from the CAM and urate deposits of the embryos incubated at 41°C for 7 to 8 days after inoculation with 1×103 sporozoites into the allantoic cavity between 9 and 12 days of age.