Crystal Containing Membrane Bound Intracellular Inclusion Bodies in the Epithelium of Experimentally Infected Sinus Mucosa

The sinus mucosa of 16 rabbits was experimentally infected with Bacteroides fragilis. This paper describes and discusses large inclusion bodies, which were found in abundance by light and electron microscopy inside ciliated cells of the sinus epithelium in 3 of the studied animals. The spindle-shaped inclusions were located in the apical portion of the cytoplasm. They were bound by a trilaminar membrane with several coils to the interior as well as to the exterior. The interior of an inclusion body consisted to a large extent of electron-lucent, floccular substance, but fibrogranular aggregates and rod-shaped crystals with a line periodicity center-to-center of about 15 nm were also conspicuous. These peculiar formations may be constituted by abnormally stored material from defective synthesis of cilia.