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Specimen Nr. 19

Specimen:

Thrombocytes, Infected joint (Sheep)

Staining:

SEM

Magnification:

6000x

Important structures :

1.Thrombocytes of a thrombus
2.Cell process of thrombocyte
3.Degenerative collagenous bundle of fibrils
Es sind Thrombozyten zu sehen, die durch Aggregation einen Thrombus bilden. Durch diesen Vorgang wandelt sich die Gestalt der Thrombozyten: sie werden kugelig und bilden viele lange Zytoplasmafortsätze aus.

Legende:

Thrombocytes of a thrombus
Cell process of thrombocyte
Degenerative collagenous bundle of fibrils

Scanning electron microscope (SEM)

It is not necessary to prepare ultra-thin sections for examinations under the scanning electron microscope because the electron beam does not penetrate the object, in contrast to transmission electron microscope (TEM).

The SEM image is created directly by a point-to-point visualization of the surface details of the specimen. To achieve this effect, a very thin electron beam scans the surface of the specimen line by line. Each surface point emits secondary electrons whose different intensities are measured by a detector.

When preparing tissue specimens for a scanning electron microscopic examination, the specimens are dried instead of embedded and sliced after fixation and dehydration.

The dehydration technique commonly used today is critical-point drying. The dried specimens are then coated with gold in a vacuum, the so-called sputtering apparatus. This covers the specimen with a surface which can emit secondary electrons.

Thrombozyten sind für die Blutgerinnung wichtig. Am Sistieren einer Blutung sind folgende Mechanismen beteiligt: die Blutungsstillung, sogenannte primäre Hämostase und die eigentliche Blutgerinnung sogenannte sekundäre Hämostase.

Direkt nach einer Gefäßverletzung setzen Thrombozyten ihre serotoninhaltigen Granula frei. Durch den Vasokonstriktor Serotonin wird die Blutung verlangsamt. Gleichzeitig haften sich die Thrombozyten im geschädigten Gebiet leicht an die Bindegewebsfasern der Wundränder an. Die agglutinierten Thrombozyten verschließen dann die Wunde vorläufig durch einen Thrombozyten-Pfropf oder Thrombus.

Thrombozyten-Phospholipide (Plättchenfaktor 3), die beim Thrombozyten-Zerfall freigesetzt werden, aktivieren dann das endogene System der Blutgerinnung. Am Ende der kaskadenartigen Kettenreaktion steht das mechanisch stabile Fibringerinnsel.
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Thrombocytes of a thrombus
Cell process of thrombocyte
Degenerative collagenous bundle of fibrils

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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