The morphology of Cowdria ruminantium is described and its staining characteristics in the vertebrate host
and in vitro are summarized. Morphologically, the organisms are characterized in the cytoplasm of endothelial
cells, macrophages and reticulo-endothelial cells. Based on the morphology of the internal structure of the
organisms, elementary (electron-dense), intermediate and reticulate bodies are identified. Each organism is
surrounded by a double membrane and a "capsule" is evident around a few organisms in vitro. Usually, only
organisms of the same form are found within a particular vacuole, although mixed colonies are described in the
in vitro studies.