Specimen Nr. 01

Specimen:

Peyer's patches, small intestine (Rabbit)

Staining:

Toluidine blue

Magnification:

50x

Important structures :

1.	Intestinal lumen
2.	Area of M (microfold) cells
3.	Germinal centre of a lymphoid follicle (secondary follicle)
4.	Interfollicular area
5.	Submucosa with blood and lymphatic vessels
6.	Muscular layer
7.	Villus
8.	Simple columnar epithelium

Die Übersichtsvergrößerung zeigt mehrere Peyersche Platten. Sie erstrecken sich von der Lamina propria der Tunica mucosa bis in die Tela submucosa. Eine besondere Region der Peyerschen Platten ist eine kappenartige Ansammlung von Lymphozyten zum Darmlumen hin, die "DOM" genannt wird. Das Epithel über den Peyerschen Platten ("Dom-Epithel") weist eher isoprismatische Zellen auf. Als weitere Besonderheit gibt es in diesem Bereich keine Zotten, Krypten und Schleim-produzierenden Becherzellen. Im Bereich der Zotten und Krypten ist das typische einschichtige hochprismatische Epithel der Enterozyten zu erkennen. Die Peyerschen Platten sind stets Sekundärfollikel mit einem aktiven Keimzentrum. Zwischen den Follikeln kann die Interfollikularregion erkannt werden.

Legende:

	Intestinal lumen
	Area of M (microfold) cells
	Germinal centre of a lymphoid follicle (secondary follicle)
	Interfollicular area
	Submucosa with blood and lymphatic vessels
	Muscular layer
	Villus
	Simple columnar epithelium

Semi-thin section

For semi-thin sections, the tissue is not embedded in paraffin (as is otherwise common for light microscopy), but in acrylic or epoxy resins, which are harder embedding substances, and permit thinner slices, so-called semi-thin slices of about 0.5 – max. 2µm in thickness, to be produced. After embedding in paraffin, a section is > 3µm thick. Semi-thin sections have better resolution under a light microscope than the thicker paraffin sections.

Embedding in epoxy resins is always performed when tissues are to be examined under a transmission electron microscope (TEM). Semi-thin sections are used to study the specimen under the light microscope before being examined under the transmission electron microscope (TEM).

Toluidine blue is primarily used to stain semi-thin sections since most dyes do not sufficiently infiltrate the epoxy resin. Toluidine blue stains various biologic components to different shades of blue.

In der Wand des gesamten Verdauungstrakts befindet sich organisiertes lymphatisches Gewebe. Man findet entweder einzelne Follikel oder Ansammlungen von mehreren Follikeln, die Peyerschen Platten, die unter einem spezialisierten Epithel liegen. Diese lymphatischen Gewebe in der Darmwand werden auch als GALT (gut-associated lymphoid tissue) zusammengefaßt. Die Peyerschen Platten findet man verstreut im gesamten Dünndarm. Sie haben keine afferenten Lymphgefäße.

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

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