Cytochemical staining of vacuolar compartments in the developing small intestine of mice

Osmium impregnation, nicotinamide adenine dinucleotide phosphatase (NADPase) and thiamine pyrophosphatase (TPPase) localisation have been applied as a cytochemical tool for the labelling of the endomembranes in the small intestinal cells of mice during embryonic development. Only cisternae of the endoplasmic reticulum were stained by prolonged osmification in the undifferentiated cells. At later developmental stage, Os-black was found in cis Golgi cisternae, small vesicles and also in the endoplasmic reticulum of some epithelial cells. At the early embryonic stage the product of NADPase reaction was visible in medial saccules of the Golgi complex and in lysosomes, while at the later stages positive staining appeared also on the apical cell surface and within the structures probably belonging to endosomal compartment. TPPase activity was constantly present in trans Golgi cisternae of the cells during the studied period of fetal life. These results indicate that the cytochemical markers for Golgi staining can also be found in several other endomembrane systems. They give the insight into various connections between the particular intracellular compartments occurring at different developmental stages.