The zinc iodide-osmium tetroxide (ZIO) technique is presently employed to study both, neural and non neural tissues. Precipitates depends on cell types and possibly cell metabol ism as well.Guinea pig cecal mucosa, already known to be composed of epithelium with cells at different maturation stages and lamina propria which i s formed by morphologically and functionally heterogeneous cell population, was studied to determine the pat tern of ZIO impregnation. For this, adult Guinea pg cecal mucosa was fixed with buffered 1.2 5% g 1 utara 1 dehyde before incubation with ZIO for 16 hours, a t 4°C in the dark. Further steps involved a quick sample dehydration in graded ethanols, embedding in Epon 812 and sectioning to observe the unstained material under a phase contrast light microscope (LM) and a transmission electron microscope (TEM).
