| Z. Kristóf, O. Tímár, K.Imre
Department of Plant Anatomy, Eötvös L. University,
Pázmány s.1/C 1117 Budapest, Hungary.
Because of the different section thickness a gap exist between
light and electron microscopy. It is almost impossible to view light microscopy
sections in conventional transmission electron microscope and vice versa.
An old requirement is to study same details first with light microscope
and then with electron microscope.
A useful solution for this problem is to make light-microscopy
sections which can then be re-embedded and subjected to ultrathin resectioning.
The most common method is to invert a resin-containing capsule on to the
section still on the glass slide and cure in situ. The main drawback of
these procedures is the long processing times due to the slow curing of
In the present study, we report our results with a technique
developed for processing the light microscopy sections for ultrathin resectioning
in such a way that the processing time is decreased from one day to a few
minutes . This method is based on sticking the section to a resin stub
with a light curable dental bond instead of the time-consuming re-embedding.
The procedure was used in the electron microscopic study on the egg apparatus
After fixation and dehydration the ovules of Torenia fournieri
were embedded in Spurr resin. 5*m thick serial sections were collected
and dried onto glass slides.
Unstained and stained (Antimonate, Acridin Orange) sections were mounted
in water and covered with a cover glass for light microscopy. Images were
grabbed through a video camera attached to the microscope. These
images were printed with a standard laser printer to help the orientation
of the ultrathin section in the electron microscope.
Alternatively, when no detailed light microscopic investigations or
good quality images were needed, the selection was carried out directly
in the inverse microscope
The selected, dried section was set in the centre of the viewing field
in the inverse microscope at low magnification. An empty resin block surface
was slightly wetted with dental bond. (ERR CSR Bond, item No. 20730).The
block was placed onto the selected section and positioned precisely. The
whole positioning was carried out on the stage of the inverse microscope.
After positioning the blue light was let through the objective. After
two minutes exposure the curing was complete and the resin block was attached
to the slide. To remove the block and detach the section from the microscope
slide a rapid cooling of the slide with liquid N2 was applied and only
a gentle force was needed to detach the section. The block was immediately
set in the ultramicrotome and resectioned. 30-70nm thick serial sections
were cut with a diamond knife without problem for conventional electron
microscopy and for elemental analysis and mapping.(fig.2.)
1.Kristóf Z. Journal of Microscopy 188(1997) 88.