Concepto de esteroides droga

 

Rotary microtome (1905) At first, histologists sectioned specimens by hand, using sharp razors. Later, around 1790, the first microtome was devised. It consisted of a wooden device with a berth to accomodate the specimen and a flat surface to slide the razor against the specimen surface, thus increasing blade purchase, regularity and thinness of the slice. The term microtome was given to these instruments by Charles Chevalier, who perfected it around 1825. Finally, around 1870, precision mechanical devices were developed. They consisted of a metal stage holding a parafin or celloidin block with the embedded piece of the tissue to be sectioned and a mechanical swing holding the blade in precise alignment with the stage. The blade is swung against the specimen´s surface by either a rotary or a rocking mechanism. Thus, serial sectioning was achieved, a very important technique for tracing neurons across the three-dimensional space of the brain. Another important development in the histological technique was staining, or adding color and opacity to the usually translucent and colorless brain cells. Although van Leeuwenhoek experimented a bit with wine spirit (alcohol) and a saffron stain to wet his specimens (particularly muscles) before observing them at the microscope, these techniques were perfected only much later, in the second half of the next century. As we will see below, they became a most important factor in the scientific development of microscopy of neural tissue, and eventually led to two Nobel awards in 1906, the very first in neuroscience.

Concepto de esteroides droga

concepto de esteroides droga

Media:

concepto de esteroides drogaconcepto de esteroides drogaconcepto de esteroides drogaconcepto de esteroides drogaconcepto de esteroides droga

http://buy-steroids.org