In 1898, Camillio Golgi reported a new cellular constituent with the form of an extensive intracellular network (the apparato reticolare interno), which now bears his name. However, the history of Golgi's apparatus is replete with controversy regarding its reality, what components of the cell should be included under its aegis, and what terminology should be used when referring to it. Electron microscopy has resolved many of these controversies and it is appropriate that this volume emphasize that aspect of Golgi apparatus discovery. The principal structural component of the Golgi apparatus is the stack of cisternae, or dictyosome. As determined both biochemically and at the level of electron microscopy, the dictyosome is a highly ordered and polarized structure. The maintenance of order within the stack is thought to result from either intercisternal bonding constituents, or filamentous structures (or both) that bridge the space between adjacent cisternae. Mechanisms proposed for movement of membrane and product into and out of the dictyosome (i.e., the Golgi apparatus stack) include a serial mode which functions exclusively by the formation, displacement, and loss of cisternae from the stack, and a parallel mode which functions exclusively by the movement of membrane, product, or precursor molecules directly into the peripheral edges of the cisternae. In the parallel mode, all cisternae can be accessed either singly or simultaneously, at least in theory, at any position within the stack. It is probable that both the serial and the parallel modes function concomitantly and need not be mutually exclusive. Finally, the peripheral tubules of the cisternae represent a major membranous constituent of the cell with potentially unique functions. These tubules interconnect cisternae of adjacent stacks and may represent the major site of receptors for the shuttle (i.e., parallel) type of transfer among cisternae. Peripheral tubules as extensions of the cisternal lumina into the cytoplasm presumably have other functions, but these, like the tubules themselves, have only rarely been accommodated into functional models of Golgi apparatus dynamics in secretion or membrane flow.

The cytoplasmic granules of the blood neutrophil leukocyte of the teleost, Ictalurus punctatus, have been shown to exhibit peroxidase activity at the light and electron microscopic levels when exposed to the 3,3′-diaminobenzidine tetrahydrochloride peroxidase procedure. Erythrocytes also show activity. The addition of cyanide to the incubation medium has no apparent effect on peroxidase reactivity in neutrophils, but inhibits pseudoperoxidase reactivity in erythrocytes. The presence of peroxidase-positive granules in the neutrophil serve as a marker for identification of this cell and strongly indicate antibacterial and phagocytic functions for the neutrophil.

Oriented fibres in the intercisternal regions of plant dictyosomes are usually associated with flattened portions of cisternae. In outer cap cells of maize roots, however, the intercisternal fibres are associated mainly with unique secretory vesicles which are elongate or kidney-shaped during their formative stages. Fibres are oriented parallel with the long axes of the vesicles even at early stages of vesicle formation. Because of their early presence and orientation, the fibres may aid in organizing and/or shaping the secretory vesicles in this tissue.