Editing Cell nucleus (section)

==History<!--'Cytoblast' redirects here-->==
[[File:Leeuwenhoek1719RedBloodCells.jpg|thumb|upright=1.5|Oldest known depiction of cells and their nuclei by [[Antonie van Leeuwenhoek]], 1719]]
[[Image:Flemming1882Tafel1Fig14.jpg|thumb|Drawing of a ''[[Chironomus]]'' [[salivary gland]] cell published by [[Walther Flemming]] in 1882. The nucleus contains [[polytene chromosome]]s.
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The nucleus was the first organelle to be discovered. What is most likely the oldest preserved drawing dates back to the early microscopist Antonie van Leeuwenhoek (1632–1723). He observed a "lumen", the nucleus, in the red blood cells of [[salmon]].<ref>{{cite book | vauthors = Van Leeuwenhoek A | title = Opera Omnia, seu Arcana Naturae ope exactissimorum Microscopiorum detecta, experimentis variis comprobata, Epistolis ad varios illustres viros J. Arnold et Delphis, A. Beman, Lugdinum Batavorum | trans-title  = The Works of, or arcana of nature by means of exactissimorum microscopes had been detected and confirmed by a variety of experiments, the Epistles to the various illustrious men of valor J. Arnold and Delphi, A. Beman, Lugdina York 1719-1730 | language = la }} Cited in {{cite book | vauthors = Gerlach D | title = Geschichte der Mikroskopie | publisher = [[Verlag Harri Deutsch]] | location = Frankfurt am Main, Germany | date = 2009 | isbn = 978-3-8171-1781-9 }}</ref> Unlike mammalian red blood cells, those of other vertebrates still contain nuclei.<ref>{{cite journal |doi=10.1007/BF01283036 |title=The cytomorphic system of anucleate non-mammalian erythrocytes |year=1982 |vauthors=Cohen WD |journal=Protoplasma |volume=113 |issue=1 |pages=23–32|bibcode=1982Prpls.113...23C |s2cid=41287948 }}</ref>

The nucleus was also described by [[Franz Bauer]] in 1804<ref name="Harris">{{cite book | vauthors = Harris H | title =The Birth of the Cell | year =1999 | publisher =Yale University Press | location =New Haven | isbn =978-0-300-07384-3 | url-access =registration | url =https://archive.org/details/birthofcell0000harr }}</ref> and in more detail in 1831 by Scottish [[botanist]] [[Robert Brown (Scottish botanist from Montrose)|Robert Brown]] in a talk at the [[Linnean Society of London]]. Brown was studying [[orchid]]s under the microscope when he observed an opaque area, which he called the "areola" or "nucleus", in the cells of the flower's outer layer.<ref name="Robert Brown">{{Cite journal |last=Brown |first=Robert |name-list-style=vanc |date=2015-04-02 |year= |editor-last=Bennett |editor-first=John Joseph |editor2-last=Brown |editor2-first=Robert |title=On the Organs and Mode of Fecundation of Orchidex and Asclepiadea |url=https://www.cambridge.org/core/product/identifier/CBO9781107775473A024/type/book_part |journal=Miscellaneous Botanical Works I |series=Cambridge Library Collection - Botany and Horticulture |location=Cambridge |publisher=Cambridge University Press |volume=1 |pages=511–514 |doi=10.1017/cbo9781107775473.017 |isbn=978-1-108-07681-4}}</ref> He did not suggest a potential function.

In 1838, [[Matthias Schleiden]] proposed that the nucleus plays a role in generating cells, thus he introduced the name "'''cytoblast'''<!--boldface per WP:R#PLA-->" ("cell builder"). He believed that he had observed new cells assembling around "cytoblasts". [[Franz Meyen]] was a strong opponent of this view, having already described cells multiplying by division and believing that many cells would have no nuclei. The idea that cells can be generated de novo, by the "cytoblast" or otherwise, contradicted work by [[Robert Remak]] (1852) and [[Rudolf Virchow]] (1855) who decisively propagated the new paradigm that cells are generated solely by cells ("{{lang|la|Omnis cellula e cellula}}"). The function of the nucleus remained unclear.<ref name="Cremer">{{cite book | last =Cremer| first =Thomas | name-list-style = vanc | title =Von der Zellenlehre zur Chromosomentheorie | year =1985 | publisher =Springer Verlag | location =Berlin, Heidelberg, New York, Tokyo | isbn = 978-3-540-13987-4}} Online Version [http://www.t-cremer.de/main_de/cremer/personen/info_T_Cremer.htm#book here]</ref>

Between 1877 and 1878, [[Oscar Hertwig]] published several studies on the [[fertilization]] of [[sea urchin]] eggs, showing that the nucleus of the [[sperm]] enters the [[oocyte]] and fuses with its nucleus. This was the first time it was suggested that an individual develops from a (single) nucleated cell. This was in contradiction to [[Ernst Haeckel]]'s theory that the complete [[phylogeny]] of a species would be repeated during embryonic development, including generation of the first nucleated cell from a "monerula", a structureless mass of primordial protoplasm ("[[Urschleim]]"). Therefore, the necessity of the sperm nucleus for fertilization was discussed for quite some time. However, Hertwig confirmed his observation in other animal groups, including [[amphibians]] and [[molluscs]]. [[Eduard Strasburger]] produced the same results for plants in 1884. This paved the way to assign the nucleus an important role in heredity. In 1873, [[August Weismann]] postulated the equivalence of the maternal and paternal germ ''cells'' for heredity. The function of the nucleus as carrier of genetic information became clear only later, after mitosis was discovered and the [[Mendelian inheritance|Mendelian rules]] were rediscovered at the beginning of the 20th century; the [[chromosome theory of heredity]] was therefore developed.<ref name ="Cremer"/>