Cytochemical localization of thiamine pyrophosphatase and nicotinamide adenine dinucleotide phosphatase activities in rat epiphyseal chondrocytes.

Two phosphatase activities, which have been reported to be associated with the Golgi apparatus in several cellular types, have been cytochemically demonstrated in rat epiphyseal cartilage. This was the case for thiamine pyrophosphatase (TPPase) which was detected in Golgi trans face cisternae and also in nascent or immature secretory granules of chondrocytes. beta-Nicotinamide adenine dinucleotide phosphatase (beta-NADPase), on the other hand, was localized mainly in the endoplasmic reticulum region of both proliferative and hypertrophic chondrocytes. Most of the beta-NADPase reaction was shown to be associated with the cytoplasmic side of the rough endoplasmic reticulum membranes and also partially dispersed throughout the cytosol background. We suggest that beta NADPase in chondrocytes could be an enzyme with different properties from that described in other secretory cells.