The detailed structure of a biological specimen, such as a cell, tissue, or organ, which can only be observed using an electron microscope.

The detailed structure of a specimen, such as a cell, tissue, or organ, that can be observed only by electron microscopy. Also called fine structure.

The physical and chemical structure of the amyloid or PrP. Often this includes the way in which the proteins are shaped.

Ultrastructure (or ultra-structure) is the detailed structure of a biological specimen, such as a cell, tissue, or organ, that can be observed by electron microscopy. It refers in general to the study of cellular structures that are too small to be seen with an optical microscope.