3-DIMENSIONAL DYNAMICS OF THE GOLGI-APPARATUS IN MITOTIC PAROTID ACINAR-CELLS - COMPUTER-AIDED RECONSTRUCTION FROM CYTOCHEMICALLY-MARKED ULTRATHIN SERIAL SECTIONS

For clarification of the structural and cytochemical dynamics of the G olgi apparatus of the parotid acinar cell during mitotic division in v ivo induced by repeated injections of isoproterenol, computer-generate d three-dimensional reconstruction was conducted of serial section ele ctron micrographs in conjunction with Golgi-specific enzyme cytochemis try. 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 ava ilable computer software program. In interphase acinar cells, the Golg i apparatus could be seen to spread out in the supranuclear region of the cytoplasm as a single continuous reticular structure with many bra nches 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 loos e 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-negati ve clusters comprised of tubulo-vesicular membranes were distributed t hroughout the cytoplasm. Recovery of the stack, single reticular conti nuity, supranuclear location and TPPase-reactivity of Golgi apparatus was apparent in daughter cells during the telophase. Distributional ch ange of the Golgi apparatus of parotid cell during mitotic division wa s clearly confirmed by the present study. Dispersion and reassembly ma y be significant factors in the equal partitioning of the Golgi appara tus into daughter cells. TPPase activity would appear quite essential to the expression of the normal cellular secretory functions.