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Specimen Nr. 07

Specimen:

Ranvier's node, Immature peripheral nerve (Mouse, 10 days old)

Staining:

TEM

Magnification:

23 000x

Important structures :

1.Schwann cell (slice with nucleus)
2.Schwann cell (slice of cytoplasm)
3.Ranvier node
4.Myelinated axon (longitudinally sliced)
5.Endoneurium
6.Basement membrane
Die Abbildung zeigt zwei längsgeschnittene markhaltige Axone. An einem dieser Axone ist ein Ranvier'scher Schnürring zu erkennen. In diesem Bereich fehlt die Markscheide. Statt dessen ist das Axon von fingerförmigen Ausläufern der Schwann'schen Zellen bedeckt. Die Myelinlamellen enden oberhalb und unterhalb des Schnürrings blind. Dabei erweitern sie sich zu sog. Taschen, die Zytoplasma der Schwann'schen Zellen enthalten. Diese Taschen zeigen eine dachziegelartige Anordnung, die durch eine schraubenförmige Wickelung der Myelinlamellen zustandekommt. Da es sich um einen unreifen peripheren Nerven handelt, besteht das Endoneurium nur aus amorpher Grundsubstanz. Am rechten und linken Bildrand sind die Anschnitte von Schwann'schen Zellen zu sehen.

Legende:

Schwann cell (slice with nucleus)
Schwann cell (slice of cytoplasm)
Ranvier node
Myelinated axon (longitudinally sliced)
Endoneurium
Basement membrane

Myelin formation in peripheral nerve fibres[bu]

1. Schwann cell
2. Mesaxon
3. Myelin lamellas
4. Axon

Transmission electron microscope (TEM)

The sections for examination under the transmission electron microscope are about 0.1µm thick. They are referred to as ultra-thin sections.

To obtain such ultra-thin sections, the tissues are embedded in plastic polymers like epon (instead of paraffin, which is used for examination under the light microscope) after fixation and dehydration. Ultra-thin sections are not stained with dyes, but contrasted with heavy-metal salts. The heavy-metal salts lead to a different electron scatter and thereby create a differentiated blackening of the photographic negative. A common method of creating contrast results with 5% uranyl acetate and lead citrate.

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Schwann cell (slice with nucleus)
Schwann cell (slice of cytoplasm)
Ranvier node
Myelinated axon (longitudinally sliced)
Endoneurium
Basement membrane

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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