Cellular compartments in mitotic cells: ultrahistochemical identification of Golgi elements in PtK-1 cells

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Abstract
This investigation focuses on the identification, distribution and transport of intracellular membrane systems during mitosis. The membranes of the Golgi apparatus can be identified cytochemically by staining for acid phosphatase (acPase) and thiamine pyrophosphatase (TPPase) activity. Using this approach the disintegration of the Golgi apparatus during mitosis was studied and the dislocation as well as the organized reappearance of Golgi elements after the completion of mitosis was followed. During mitosis the activity of both enzymes is strong enough to react with the substrate applied during the staining procedure. A characteristic pattern of membrane distribution in mitotic cells was observed. During interphase the TPPase reaction is characteristically limited to 1 or 2 cisternae of a dictyosomal stack. The acPase reaction stains the membranes of the total stack, of the GERL, of some vesicles and cisternae near the dictyosomes and lysosomes. After the mitotic breakdown of the dictyosomal stacks the forming vesicles still stain positively and are distributed over the entire cytoplasm. At late anaphase and early telophase the enzyme activity ocurs not only in the reconstituting dictyosomes but also in the nuclear envelope and in some ER cisternae. The extended spectrum of membrane structures indicating Golgi enzyme activity becomes obvious. This phenomenon favors the idea that at least some functions of the Golgi apparatus persist during mitosis.