Make a SKIN a sectional representation containing both cutan

Solution

Fixation is done to preserve the specimen to be the same as living material.The skin specimen is immediately put in formalin solution(in particular formaldehyde and glutaraldehyde) to prepare normal histological section.It is kept in this solution for a minimum of 24 hours before processing it. The skin tissue is fixed by formalin by making cross links between residue of lysine(free amino groups) lying in the proteins without altering its structure. A pH of 7 is maintained by buffering it with phosphate to stop acidity triggered by tissue hypoxia. Parts of the specimen are kept on into small plastic cassettes which hold them and recognize during during the processing and also act as the support for the final paraffin block which was initially kept into fixative. These paraffin blocks are then set to permit the tissue to be cut into thin sections. With the help of an automated processor the tissue is dehydrated with alcohol and all the water is removed. Xylene is used for removing alcohol and the tissue gets prepared to be embedded in paraffin wax. The tissue is removed carefully from the cassette and put into mould over which hot paraffin wax is poured. When the wax cools down the block is ready for sectioning. By using a microtome which shifts the block across a very precise knife the embedded tissue is cut into sections of about 3-5 microns. These sections are kept over warm water bath and are placed on a glass slide by picking them up and drying in an oven. The slide is then stained generally by haematoxylin and eosin. This stained slide is again gone through water,alcohol and xylene. To glue the cover slip on the slide a resin is applied over it. Transmission electron microscopy is a technique in which high beam of electrons is passed through an ultrathin specimen like skin. As the electrons are passed through the specimen they interact with it and forms a magnified image focused with the help of an objective lens and can be seen on a fluorescent screen. To view a specimen through this technique the first stage is to fix the specimen. Sectioning of the sample is done to permit us to view the cross section(in this case subcutaneous tissue) to see the ultra structure present inside along with the outer layer(cutaneous) of the skin by spraying a heavy metal at a tilted angle over it and which gets coated on it which produces effect of a shadow and produces a three dimensional structure.