For clarification of the structural and cytochemical dynamics of the Golgi apparatus of the parotid acinar cell during mitotic division in vivo induced by repeated injections of isoproterenol, computer-generated three-dimensional reconstruction was conducted of serial section electron micrographs in conjunction with Golgispecific enzyme cytochemistry. Outlines of the cells, nuclei, thiamine pyrophosphatase (TPPase) -positive Golgi elements (trans Golgi) and TPPase-negative ones (middle/cis Golgi) could be clearly seen through the use of a commercially available computer software program.
In interphase acinar cells, the Golgi apparatus could be seen to spread out in the supranuclear region of the cytoplasm as a single continuous reticular structure with many branches and anastomosis. TPPase-positive trans elements were associated with the entire surface of the interphase Golgi stack. With the start of the mitotic phase, gradual disorganization of the stack into a loose structure followed by dispersion throughout the cytoplasm and marked disappearance of TPPase activity became evident. Up to the anaphase, the Golgi apparatus was completely disorganized as small TPPase-negative clusters comprised of tubulo-vesicular membranes were distributed throughout the cytoplasm. Recovery of the stack, single reticular continuity, supranuclear location and TPPase-reactivity of Golgi apparatus was apparent in daughter cells during the telophase. Distributional change of the Golgi apparatus of parotid cell during mitotic division was clearly confirmed by the present study. Dispersion and reassembly may be significant factors in the equal partitioning of the Golgi apparatus into daughter cells. TPPase activity would appear quite essential to the expression of the normal cellular secretory functions.