K. Weipoltshammer et al., Signal enhancement at the electron microscopic level using Nanogold and gold-based autometallography, HISTOCHEM C, 114(6), 2000, pp. 489-495
Immunoelectron microscopy using ultrasmall gold markers is a very sensitive
method to detect molecules at high resolution. In order to discriminate th
e gold particles in the electron microscope, enlargement of gold particles
is necessary. So far, mostly silver ions were used for deposition onto the
surface of gold grains. In our study, we tested the selective deposition of
gold instead of silver ions to enlarge gold particles. This was performed
following immunogold detection of DNA at the surface of ultrathin sections
embedded in the acrylic resin LR White (postembedding approach). Morphometr
ic analysis of the distribution of DNA in human spermatocytes revealed that
the method offers very good specificity and sensitivity and therefore is a
good alternative to the use of silver for signal enhancement. This techniq
ue was also applied to the detection of ribosomal genes in human testis at
the electron microscopic level by in situ hybridization. Ribosomal genes we
re localized in peri- and intranucleolar chromatin as well as in the dense
fibrillar component of nucleoli.