All the material used in this ATLAS, independent of the microscope used to visualized had to be fixed shortly after its removal. The process of fixation changes a little from light to electron microscope. In general the material analyzed in light microscopy was fixed in a solution containing formaldehyde 10% in buffer and the samples observed in the electron microscope were fixed in a solution containing 2.5% of gluteraldehyde and 4% of paraformoldehyde in buffer. All material were kept in 4⁰ Celsius.

 After the fixation, the samples were rinsed several times, dehydrated and included in resin, (the type of resin used also varies in function of the microscope used, light or transmission electron)  the material  must be sectioned. In light microscopy, we use a equipment called Microtome, to obtain sections with  thickness of few micrometers (1mm = 10^-6 m).

 The sections were collected using a slide, and after few steps the samples were stained with different types of stainning solutions. The most famous stainning solution is the Hematoxiline & Eosin. This solution called by H&E stains the nucleus in purple and the cytoplasm in rose.
    After drying, the slides must be mounted with a coverslip. To do so,  a drop of mounting oil is settle over the material and the coverslip is sealed. The slide is now ready to be observed in the light microscope.

 The samples that will be observed in the transmission electron microscope (TEM) must also be sectionned. This is performed in an equipment called Ultramicrotome. The sections obtained in this equipment are in the range of 40 - 60 nanometers  (1nm= 10^-3mm), in order to be crossed by the electron beam.  The sections were collected with very small grids and as happened with the light microscope, must be stainned previously to the observation.  To perform that  we use solutions containing metals with high atomic number, such as  lead, uranium and osmius.