Structure of the Trophozoite and Cyst

  • Dennis E. Feely
  • Stanley L. Erlandsen
  • David G. Chase


In a letter to the Royal Society in 1681, Anton van Leeuwenhoek reported the microscopic observations of his own diarrheic stool (Dobell, 1920). Unfortunately, he made no drawings of the organism he saw, but his description is detailed and vivid enough to convince many that what he saw was Giardia duodenalis. His letter is also the first association of this parasite with intestinal disease. Leeuwenhoek’s description of the trophozoite includes the presence of flagella (“sundry little paws”), the ventral disc, shape, size, and motile behavior. The first formal description of G. duodenalis was made by Lambl (1859), in which he describes size, shape, and the presence of the ventral disc. Grassi (1879, 1881) improved on previous work by describing the presence of flagella and nuclei in the trophozoite and making the first description of the cyst. Detailed light microscopic descriptions of the trophozoite and cyst have been published by Simon (1921) and Filice (1952). The monograph by Filice provides the most complete work on the morphology of the trophozoites and cysts of G. agilis, G. duodenalis, and G. muris. His proposed definitions of the three species are adopted in this chapter.


Cyst Wall Basal Body Bare Area Median Body Giardia Cyst 
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Copyright information

© Springer Science+Business Media New York 1984

Authors and Affiliations

  • Dennis E. Feely
    • 1
  • Stanley L. Erlandsen
    • 2
  • David G. Chase
    • 3
  1. 1.Department of Oral Biology, College of DentistryUniversity of Nebraska Medical CenterLincolnUSA
  2. 2.Department of Anatomy, School of MedicineUniversity of MinnesotaMinneapolisUSA
  3. 3.Cell Biology LaboratoryVeterans Administration HospitalSepulvedaUSA

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