******************************************************************
LABORATORY
EXERCISE: Using virtual
Slide 35 of lymph node and 36 of
spleen identify the respective cells described above with the
aid of your Digital Histology CD.
Visual Histology CD. You will not have
to identify FDCs on these slides but you will have to identify
them on electron micrographs. You may study these electron micrographs
of FDCs on the website entitled: "The FDC Network"
--- (URL: >> http://users.vcu.org/~aszakal/fdc_network/index.html
<< ). On the virtual slides identify the following cell
types: 1. Small lymphocytes in the cortex (mantle)
and in smaller numbers in the germinal center (GC). 2.
Medium lymphocytes; These are present mainly in thegerminal
centers. The medium lymphocytes will be
all over the GC. These cells have a euchromatic nucleus that is
mostly oval and a cytoplasm surrounding the nucleus which is well
visible on all sides. 3. Immunoblasts are the largest B
lymphocytes of the GC. They have a large euchromatic nucleus with
a distinct peninsula-shaped nucleolus. This nucleolus have a round
profile in cross section. These cells have ample cytoplasm all
around the nucleus but no visible cytoplasmic inclusions. 4.
The Tingible Body Macrophage (TBM) and the FDCs are the largest
cells of the GC. The TBM has a similar euchromatic nucleus to
the nucleus of immunoblasts, but only a spherical nucleolus. The
TBM nucleus is slightly smaller. The cytoplasm of TBM is
large and irregular in outline, extending among the surrounding
cells. The diagnostic features of the TBM are the basophilic
(dark) "tingible bodies" in its cytoplasm which
are remnants of phagocytized, apoptotic B lymphocytes. 5.
Also, you should identify the mitotic figures (B cells
in various stages of mitosis). 6. Reticular cells can
be identified by their euchromatic nucleus which is smaller than
those of immunoblasts and TBMs. These reticular cells can be seen
primarily at the margins of the GC and among the small lymphocytes
in the cortex of the lymphoid nodule. All of these cells are identified
on the Digital Histology CD.
******************************************************************
For
actual images CLICK on the FDCs or Immunoblasts or TBMs