Degree Type


Date of Award


Degree Name

Doctor of Philosophy



First Advisor

Edwin C. Powell


Ring doves (Streptopelia risoria) were orally infected with virulent palatotropic Trichomonas gallinae to address problems concerning caseous nodule (canker) formation and progression with light, scanning and transmission electron microscopy. Trichomonads initially attacked microvilli-like apical processes of palatal squamous cells as well as epithelial cell borders. Epithelial damage was associated with the phagocytosis of apical processes whereas mechanical removal of damaged and loosened cells by trichomonads was evident and pathological desquamation was pronounced. Trichomonads were invasive although they did not appear to traverse the basement membrane. The concomitant inflammatory response involved granulocytes and macrophages and the infiltration of these cells through dilated intercellular spaces to areas beneath parasites. Areas beneath cankers served as sites of trichomonad destruction by histiocytes and contained much tissue debris;Ancillary studies concerning trichomonad culture and transmission were conducted. Parasites isolated in STS medium containing 10% fetal bovine serum and a commercial growth supplement gave better growth than serum alone. It was shown also that differences between bovine calf serum and newborn calf serum, with and without growth supplement, were minor;Transmission of T.gallinae by natural means was examined. Transmission from parent to young via crop milk was extremely efficient in causing avian trichomoniasis as was transmission through water sources;An improved technique for trichomonad preparation for scanning electron microscopy was offered. Longer fixation schedules, the use of phosphate buffer and the inclusion of a mordanting step involving tannic acid and guanidine hydrochloride allowed tissue samples to be air dried from freon 113 with minimal shrinkage and swelling artifacts. Comparable tissue samples processed in phosphate and cacodylate buffers, not mordanted and critical point dried possessed greater numbers of artifacts.



Digital Repository @ Iowa State University,

Copyright Owner

Glenn Ernest Kietzmann, Jr.



Proquest ID


File Format


File Size

148 pages

Included in

Zoology Commons