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The Invention Of Phase Contrast Microscopy By The Nobel Prize Winner Frits Zernike

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Abstract
In the last century with the invention of phase contrast microscopy by the Nobel Prize winner Frits Zernike, nucleoli were among the most con-spicuous structures. The nucleolus was first de-scribed between 1835 and 1839, but it had to go through another century before it was discovered to be related with a specific chromosomal locus, which marked it as a cytogenetic entity.1
At the end of the 18th century, Montgomery was the first to publish the monumental monograph, which included color figures of nuclei and nucleo-li.1
Based on the Montgomery work, further studies where conducted to analyze the function of the nucleolus in the next century. In fact himself has studied nucleoli in the oocytes of over 175 differ-ent species and had approached at three re-markable conclusions that still hold true today: 1) In one cell there can be more than one nucleolus;
2) Cells with higher growth are presented with more and larger size;
3) The last conclusion was, the size of the cells interfere with the size of nucleolus.2
After the 1960 numerous discovers made a huge impact in the modern science, one of these is the study on the rRNA which lead to the conclusion that the nucleolus is the site of ribosomal RNA synthesis and nascent ribosome assembly.1
In the early 70s it was observed that the ribonu-cleoprotein precursors to ribosomes contain two classes of protein. The difference between these proteins was thought to be that one class could be recognized as ribosomal proteins,

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