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Specimen Nr. 03B

Specimen:

Perineurium N. occipitalis major (Human being)

Staining:

SEM

Magnification:

10000x

Important structures :

1.Collagen fibre
2.Collagen fibrils
Das rasterelektronenmikroskopische Präparat zeigt eine kollagene Faser aus dem Epineurium des Nervus occipitalis major. Die Kollagenfibrillen, deren periodische Streifung hier nicht sichtbar ist, ordnen sich parallel zueinander an. Der Durchmesser der kollagenen Faser wird durch die Anzahl der Kollagenfibrillen bestimmt.

Legende:

Collagen fibre
Collagen fibrils

Collagen fibre[sl]

1. Collagen fibre
2. Bundle of collagen fibres
3. Microfibrils

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.



Die Untereinheiten kollagener Fasern heißen Kollagenfibrillen. Ihr Durchmesser beträgt durchschnittlich 0,2-0,5 µm. Die Bildung dieser Fibrillen erfolgt teilweise intrazellulär in den Fibroblasten (Polypeptidsynthese - Hydroxylierung und Glykosylierung - Bildung der Tripelhelix - Sezernierung des Prokollagens) und teilweise extrazellulär. Indem sich einzelne Tropokollagenbündel zusammenlagern, entstehen Mikrofibrillen. Mikrofibrillen sind die Untereinheiten der Kollagenfibrillen. Durch kovalente Vernetzung der Mikrofibrillen (Querbrücken aus Lysinaldehyden und Hydroxylysinresten) entstehen Kollagenfibrillen.

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Magnification:

3000x

Magnification:

10000x

Magnifications
Collagen fibre
Collagen fibre
Collagen 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

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

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