BNL STEM specimen example:   Unstained Bacteriophage T4.

A freeze-dried preparation of bacteriophage T4 and TMV. The virus consists of a head (normally full of double-stranded DNA), a tail tube, a baseplate at the end of the tail tube and thin tail fibers attached to the base plate. The particle at the lower right has lost its DNA. The mass per unit length of a tail fiber is 866 +/- 76 kDa, indicating it is a trimer. The full-scale of the dark-field micrograph is 0.512 microns.