The detection of P and Ca by X-ray microanalysis in the cyto-chemical reaction product of alkaline phosphatase in the epithelial surface of the rat duodenum
Alkaline phosphatase activity (ALP-ase) can be localized both over the brush border and on the lateral wall of the duodenal columnar epithelium. (Figs.1,2). Dense precipitate can also be observed on or in the mucus ‘bodies’present on the luminal surface. (Figs.3,4). In order to find out whether it is real phosphatase reaction product(lead phosphate) or not, unstained semi-thin sections (3-500 nm) of glutaraldehyde- fixed tissue, were subjected to X-ray microanalysis, after being incubated in an appropriate substrate medium (Mayahara's lead citrate method), post-fixed in buffered OsO4, and embedded in Spurr resin. A scanning transmission electron micrograph(STEM) was first taken at 25-50 kv(JEOL 50A SEM or 100 C TEM),after which the section was analysed by either a wavelength dispersive detector attached to the SEM or an energy dispersive type enfaced to the TEM at 40-60 kv.