ATOMIC-FORCE MICROSCOPY OF HISTOLOGICAL SECTIONS USING A NEW ELECTRON-BEAM ETCHING METHOD

In order to examine histological sections of the rat vomeronasal epith elium with the atomic force microscope (AFM), we developed an electron beam etching method that improves the resolution of AFM images. This method results in AFM images comparable to those obtained with the tra nsmission electron microscope (TEM). Ultrathin tissue sections embedde d in epoxy resin were observed before and after the treatment with ele ctron beam radiation. Before electron beam treatment, epithelial struc tures such as the microvilli surface, dendritic processes, the support ing cell layers and the neuronal cell layers were all visible using th e AFM. However, only a few subcellular structures could also be resolv ed. The AFM images were not as clear as those obtained with the TEM. A fter electron beam treatment, however, the resolution of AFM images wa s greatly improved. Most of the subcellular structures observed in TEM images, including the inner membrane of mitochondria, ciliary-structu re precursor body, junctional complexes between the neurons and suppor ting cells, and individual microvilli were now visible in the AFM imag es. The electron beam treatment appeared to melt the embedding resin, bringing subcellular structures into high relief. The result of this s tudy suggests that electron beam etching of histological samples may p rovide a new method for the study of subcellular structure using the A FM.