Three-dimensional reconstruction of the Golgi apparatus in osteoclasts by a combination of NADPase cytochemistry and serial section scanning electron microscopy.

The three-dimensional morphology of the Golgi apparatus in osteoclasts was investigated by computer-aided reconstruction. Rat femora were treated for nicotinamide adenine dinucleotide phosphatase (NADPase) cytochemistry, and light microscopy was used to select several osteoclasts in serial semi-thin sections to investigate the Golgi apparatus by backscattered electron-mode scanning electron microscopy. Lace-like structures with strong backscattered electron signals were observed around the nuclei. These structures, observed within the Golgi apparatus, were attributed to the reaction products (i.e., lead precipitates) of NADPase cytochemistry. Features on the images corresponding to the Golgi apparatus, nuclei, and ruffled border were manually traced and three-dimensionally reconstructed using ImageJ/Fiji (an open-source image processing package). In the reconstructed model, the Golgi apparatus formed an almost-continuous structure with a basket-like configuration, which surrounded all the nuclei and also partitioned them. This peculiar three-dimensional morphology of the Golgi apparatus was discovered for the first time in this study. On the basis of the location of the cis- and trans-sides of the Golgi apparatus and the reported results of previous studies, we postulated that the nuclear membrane synthesized specific proteins in the osteoclasts and, accordingly, the Golgi apparatus accumulated around the nuclei as a receptacle.