An ultrastructural study of the formation of "dark" and "light" cytoplasmic inclusions by murine cytomegalovirus in mouse submandibular gland.

Electron micrographs of acinar cells of the submandibular glands of CFW mice infected with murine cytomegalovirus, Smith strain, were studied. The resulting viral intracytoplasmic inclusion bodies were classified into two groups termed "light" (relatively electron-lucent) and "dark" (relatively electron-dense). It appeared that the "dark" type was the late stage of inclusion body maturation.