Specimen Nr. 03

Specimen:

Hyaline cartilage, Joint cartilage (Sheep)

Staining:

TEM

Magnification:

6440x

Important structures :

1.	Interterritorial cartilage matrix
2.	Pericellular cartilage matrix with protruding condrocyte processes
3.	Rough endoplasmatic reticulum
4.	Golgi apparatus
5.	Mitochondria
6.	Electron dense bodies surrounded by interterritorial matrix

Im transmissionselektronenmikroskopischen Bild ist zu erkennen, daß die lichtmikroskopisch homogen erscheinende extrazelluläre Matrix aus sich überkreuzenden kollagenen Fibrillen besteht. Unmittelbar um den Chondrozyten weisen diese einen geringeren Durchmesser auf als in weiterer Entfernung. Dieser Bereich wird elektronemikroskopisch als perizelluläre Matrix bezeichnet. Er entspricht im Lichtmikroskop dem Knorpelhof. Die elektronendichten, in der Matrix befindlichen Körperchen sind die sog. electron dense bodies. Wichtige Zellorganellen des Chondrozyten sind das endoplasmatische Retikulum, der Golgi-Komplex und Mitochondrien.

Legende:

	Interterritorial cartilage matrix
	Pericellular cartilage matrix with protruding condrocyte processes
	Rough endoplasmatic reticulum
	Golgi apparatus
	Mitochondria
	Electron dense bodies surrounded by interterritorial matrix

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.

Im rauhen endoplasmatischen Retikulum und Golgi-Komplex des Chrondozyten werden die Vorläufer der kollagenen Fibrillen und der Glykosaminoglykane der extrazellulären Matrix gebildet. Neben der Syntheseleistung besteht eine wichtige Funktion des Golgi-Komplexes in der Konzentration und "Verpackung" der Syntheseprodukte. Die Sekretgranula, über die die synthetisierten Produkte an die Zellumgebung abgegeben werden, sollen hier ihre umhüllende Membran erhalten.

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!