The Relationship of Population Growth to In vitro Encystation of Endamoeba histolytica

Cultivationin vitroofEndolimax blattaeLucas, 1927 from the cockroach hind gut

“…In the present work, although few cultures were used and conclusions reached can only be regarded as tentative, encystment of Endolimax blattae in vitro at Cultivation of Endolimax blattae 185 25 °C also seemed to be related to starch depletion in the culture. In Entamoeba histolytica, on the other hand, the rapid growth and overcrowding of amoebae which result from transfer from starch-free medium to medium containing starch seem to bring about encystment (Dobell & Laidlaw, 1926;Cleveland & Sanders, 1930;Everritt, 1950). McConnachie (1955) explained the difference in response of E. histolytica and E. invadens to presence or absence of starch on the basis of different conditions in their respective hosts.…”

IN VITRO GROWTH AND METABOLISM OF ENDAMOEBA HISTOLYTICA

“…Using different strains of amoebae and culture methods, the results in TABLE 5 show that the first group of workers obtained shorter generation times when much smaller inocula per unit volume of media were used. Everritt (1950) was not able to increase yields proportionately or decrease generation times by increasing the inoculum ten-fold-an inoculum that more nearly approaches the number of amoebae used to seed our perfusion jar cultures. Brackett and Bliznick (1947), using 15-5200 amoebae of the NIH 103 strain per tube and an incubation period of 3 to 6 days, obtained 2 to 2.5 divisions per day.…”

“…Buchanan and Fulmer, 1928) shown in TABLE 4, the average generation time of HK-9 trophozoites grown in PJ cultures is about 4.9 hours. For comparative purposes, we have attempted to interpret and calculate generation times from growth curves given by Balamuth and Howard (1946) and from total yields obtained by Everritt (1950). Using different strains of amoebae and culture methods, the results in TABLE 5 show that the first group of workers obtained shorter generation times when much smaller inocula per unit volume of media were used.…”

Temperature adaptation of Entamoeba histolytica and its effect on virulence

“…When this prolific rate of multiplication was at its maximum, it is possible that the "sharp rise" of potential accompanied by mass encystation took place. It is also possible (Everritt, 1950) that the prolific rate of multiplication led to overpopulation and accumulation of large amounts of metabolic by-products which in turn led to encystation.…”