Circumstantial Evidence of an Extracellular (Epicellular) Localization of Developmental Stages of Cryptosporidium

Abstract

Goccidian parasites of the genus Cryptosporidium have been reported in a variety of host species. Within the host, developmental stages of Cryptosporidium occur on the luminal surface of epithelial cells of the gastrointestinal and/or respiratory tract. The developing organisms are covered by an envelope of uniform thickness, consisting of 2 unit membranes and an intervening thin cytoplasmic layer. When observed in thin sections, the enveloped organisms appear to rest on a dense band (layer), on the surface of the host cells.