Changes in the generation cycle of duodenal crypt cells in chickens infected with Eimeria acervulina

Summary Changes in the duration of the progenitor cycle and its four phases were determined for duodenal crypt cells in chickens infected with Eimeria acervulina. Metaphase curves were constructed using percent labelled metaphase nuclei in duodenal crypt cells at short intervals after the injection of [³H]thymidine. The duration of the progenitor cycle and its four phases were calculated using the synthetic index and data obtained from the metaphase curves. The cycle time was reduced from 14 h in control birds to 10.2 h at 2 days and 10.6 h at 4 days postinfection. The change was attributable entirely to a reduction in G₁ or the presynthetic phase. In addition, the population of dividing cells within each duodenal crypt was almost doubled in infected birds. These increases in cell production precedes all the histological changes observed earlier in the intestines of E. acervulina infected chickens. At least in this instance, changes in crypt morphology seems, therefore, to result from an induced change in the functional activity of the crypt.