Three-Dimensional Ultrastructure of the Golgi Apparatus In Vivo: Scanning Electron Microscopy of Osmium-Macerated Mammalian Cells.

The osmium maceration method remains the only technique that enables direct three-dimensional (3D) visualization of subcellular structures via scanning electron microscopy (SEM), and it is particularly effective for resolving spatially complex organelles such as the Golgi apparatus. Here, we describe the 3D ultrastructure of the Golgi apparatus in various cell types, including epididymal epithelial principal cells, intestinal goblet cells, pituitary gonadotropes, and spinal ganglion cells, processed using the osmium maceration method. The overall morphology of the Golgi apparatus varied between cell types, exhibiting a range of configurations, including cup-shaped and spherical forms. Within the Golgi stacks, the cis-most cisterna and the trans-Golgi network displayed especially distinct structural characteristics. The cis-most cisterna typically appeared as a flat sheet with numerous fenestrations, a feature consistently observed across all four cell types. In contrast, the 3D organization of the trans-Golgi network, comprising tubules and/or plate-like membranes frequently interconnected to form elaborate architectures, varied according to the cell type. The morphological diversity of the Golgi apparatus in three dimensions likely reflects functional and structural specializations among different cell types.