Specimen Nr. 06D

Specimen:

Spleen (Rat), immunologic reaction, secondary follicle

Staining:

Peroxidase, anti-perosidase technique and alkaline phosphatase anti-alkaline-phosphatase (blue and red) technique, nucleus stained with hemalaun

Magnification:

400x

Important structures :

1.	Germinal centre of a lymphoid follicle (secondary follicle)
2.	Corona of a secondary lymphoid follicle
3.	Macrophages

Mit Antikörpern sind immunhistochemisch in blau IgD-positive B-Lymphozyten dargestellt, die sich vorwiegend in Primärfollikeln und der Korona von Sekundärfollikeln aufhalten. In braun sind alle Zellen identifiziert, die DNA-Strangbrüche aufweisen, und damit als Zellen ausgewiesen sind, die den programmierten Zelltod ausführen (Apoptose). Diese werden sehr schnell von Makrophagen phagozytiert. Neben der Rinde des Thymus weist das Keimzentrum eines Sekundärfollikels die meisten apoptotischen Lymphozyten des Körpers auf.

Legende:

	Germinal centre of a lymphoid follicle (secondary follicle)
	Corona of a secondary lymphoid follicle
	Macrophages

Immunohistochemestry

Immunohistochemistry is used to confirm the presence of or to identify certain structures or substances in tissue sections which cannot be identified with conventional staining methods. Such structures include: cells, enzymes, hormones, macromolecules like nucleic acids and polysaccharides. The basis of immunohistochemical staining techniques is the antigen-antibody reaction. This method makes it possible to differentiate, for example, various cells in a tissue section according to their different metabolic products or surfaces. Either the metabolic product or a certain surface component serves as the antigen. In the first step, the antigen reacts with a specific antibody. The resulting antigen-antibody complex is invisible. Therefore, in a further step a second antibody bound to an adjuvant is added and binds to the initial antibody (so-called sandwich procedure). The bound adjuvant makes the antigen-antibody complex visible under the microscope and identifies the sought structure. Adjuvants are:

fluorescent dyes:
fluoresce by stimulation under UV light
enzymes:
catalyze a definite dye reaction
particular markers:
The immune complexes can be made visible with, e.g. bound gold particles, both in direct light and under the electron microscope.
radionuclids:
The substance sought is identified by blackening a photographic plate or an applied photo film.

Combination with further dyes or staining techniques:

hemalaun
dye for staining cell nuclei
result: Cell nuclei turn an intense blue.

Zum einen verlassen Zellen das Keimzentrum, die überwiegend in der roten Pulpa oder im Knochenmark zu Plasmazellen werden. Diese produzieren sofort und für lange Zeit Antikörper, die viele Gewebe des Körpers auf dem Blutweg erreichen können (humorale Immunantwort). Zum anderen verlassen Zellen das Keimzentrum, die zu Gedächtnis B-Lymphozyten werden. Sie zirkulieren ständig durch die Organe des Körpers, und können im Vergleich zu naiven B-Lymphozyten bei einem zweiten Treffen mit demselben Antigen schneller und in größerer Menge Antikörper produzieren.

HistoNet2000 - Help

1. Organization of the screen surface

Right side: histologic specimen
Left side: information about the specimen (above) and general program functions (below)

2.Histologic specimen

Pull the mouse across the histologic specimen for training purposes. A small square with exclamation marks (dynamic labels) will appear where there is an important structure. You should then decide what structure this could be. To check your result, simply click the appropriate square, and the correct label will appear. The option “marked” allows you to see all labels for all structures simultaneously. These can be removed by clicking “unmarked”. This reactivates the dynamic labels.

3. Complementary information

Info: general information about the specimen, as well as a list of the dynamic labels
Drawing: schematic drawing of the specimen
Staining: information about the staining method for this specimen
Knowledge: short texts with basic histologic information, presently deactivated

4. General Program Functions

Home: returns you to the “start” page
Tutor: how to contact the HistoNet Team
Help: Instructions for Use appear
Exit: closes down the HistoNet program
Boxes: goes back to the other specimen of a topic
VM: provides virtual microscopy

We hope you will enjoy working with HistoNet2000 and learn a lot from it!