But as a general rule, the actual appearance of the stained material or structure in microscope sections depends on how thick the stain is. Hence they don't absorb so much light per unit thickness of the section, and thus the apparent intensity of staining is reduced. You also expect to see dense nucleoli in these vesicular nuclei. As a first approximation when you are attempting to identify a cell type, the combination of a basophilic cytoplasm and a vesicular nucleus sporting prominent nucleoli is a pretty good clue that the cell in question is secretory, and more to the point, it is secreting proteins. Secretory nuclear morphology can be seen on slide 552 in neuron cell bodies.
Neurons are very active secretory cells, producing proteins for transport out of the cell.
To see an example of this type of nuclear morphology, click here. Even with special routines, the level of detail visible in the LM is not too high, and the electron microscope is needed to get resolution high enough to make out the internal structure of, say, mitochondria. Mitochondria Much to many people's surprise, mitochondria are visible in the light microscope. It requires a special stain to make them visible. Hence they are at the limit of resolution of even very good light microscopes.