Three-dimensional architecture of the Golgi complex observed by high resolution scanning electron microscopy.

In spite of many light and transmission electron microscopic studies of the Golgi complex, many important points remain unsettled. Recently, we have devised a method of observing the three-dimensional configurations of intracellular structures by scanning electron microscopy. We have used this method to study the three-dimensional structure of the Golgi complex in several tissues of the rat, paying special attention to three problems: the overall configuration; the spatial construction of each stack, and the relationship to neighbouring organelles. The interconnected stacks which form the Golgi complex are arranged in a manner characteristic of the particular cell type. In rat extraorbital lacrimal gland the stacks form an irregular network spread throughout the cell, while in anterior pituitary cells they form a hollow sphere. Continuities were seen between cisternae within a stack, and in one case a stack actually consisted of one helically wound cisterna. We also observed slender tubules connecting Golgi stacks to neighbouring rough endoplasmic reticulum. Vesicles, presumably transport vesicles, were frequently observed on the surface of the cisternae, most commonly at the cisternal rims. However the continuities among stacks and connections with cisternae and with the rough endoplasmic reticulum demonstrated here offer alternative routes for movement of substances through the cellular endomembrane system.