Das Bild zeigt einen Längsschnitt durch ein fetales Kniegelenk. Sowohl am Femur als auch an der Tibia spielen sich Ossifikationsvorgänge ab. Zwischen Epiphyse und Diaphyse der Tibia ist die Epiphysenfuge zu erkennen, d.h. der Bereich, in dem die enchondrale Verknöcherung abläuft. An der Diaphyse der Tibia ist die perichondral entstandene Knochenmanschette von den enchondral gebildeten diaphysären Knochenbälkchen zu unterscheiden.

Legende:

	Epiphysis of distal femoral condyle
	Epiphysis of proximal tibial condyle
	Patella (kneecap)
	Knee joint space
	Perichondral bone anulus
	Diaphysial bone trabeculae
	Epiphyseal plate
	Muscle tissue
	Skin

Hematoxylin and Eosin (H&E)

H&E is the most common survey stain, which shows cell nuclei and cytoplasmatic components.

Structures	Colour
Nuclei	blue
Cytoplasm	pale red
Connective-tissue fibres - Collagen - Reticular - Elastic	red - pale rose to red
Muscle tissue	red
Erythrocytes	red-orange

Dyes:

Hematoxylin

(e.g. hemalaun, Weigerts or Heidenhains iron-hematoxylin)
Hematoxylin is a positively charged dye (at low pH values). It therefore colors negatively charged (basophilic) structures blue, like the DNA of nuclear chromatin, the RNA of rough endoplasmatic reticulum, and the acidic glycosaminoglycans of hyaline cartilage.
Hematoxylin used in the preparation of iron varnish is Weigerts or Heidenhains iron-hematoxylin and in the preparation of aluminum varnish is hemalaun.

Eosin

Eosin is a negatively charged dye used for counterstaining. It stains all remaining structures different shades of red (acidophilic).

Thiazinrot

Thiazinrot behaves similar as eosin.

Bei der enchondralen Ossifikation wird unterschieden:

Die perichondrale Knochenbildung, die zu Beginn jeder enchondralen Ossifikation in der Mitte der Diaphyse abläuft, sich epiphysenwärts ausdehnt und zur Versteifung des hyalinknorpelig angelegten Skelettstücks führt. Diese Ossifikationsvorgänge laufen in gleicher Weise ab wie bei der desmalen Ossifikation.
Die enchondrale Knochenbildung, bei der zunächst der präformierte Knorpel aufgelöst wird, bevor Knochen neu gebildet wird. Dieser heißt Ersatzknochen, die Art der Ossifikation enchondrale oder indirekte Ossifikation.

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!

Specimen Nr. 02A

Specimen:

Staining:

Magnification:

Important structures :

Legende:

Hematoxylin and Eosin (H&E)

Dyes:

HistoNet2000 - Help