Is there any way to quickly stain paraffin sections so that I can evaluate whether or not I need to cut further into the block?
We used to use a cotton ball moistened with dilute methylene blue to wipe over the surface of the block. This gave us a good idea of the tissue at that level and helped greatly in the orientation. If you prefer you can always place a cut section on a slide and add several drops of dilute aqueous methylene blue (say 0.05-0.1%), this also works well. No need to mount the section.
If the structure is fairly large you can use a pseudo-interference contrast illumination method to see structure in the section. Just move the objective of the microscope slightly to one side of its normal position and you can see 3D structure without doing any deparaffinizing or staining. You will be surprised how much detail you can make out. This is a great method for finding glomeruli in kidney frozens.
Centers for Disease Control
I have used the following technique when searching for glomeruli in kidney biopsies.
Mount the section on the slide as usual.
Place the slide on the microscope stage, under a 10x objective.
Close the condenser aperture down, and lower the entire condenser
away from the microscope stage.
What should result is a slightly out of focus image of the unstained tissue section. You may have to adjust the settings of the aperture and condenser. This works well for large structures such as the glomerulus in the nephron of a kidney.
Patrick M. Haley