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Cytology or Cell Biology, which is Study of Cells, gained prominent status with discoveries German scientists Schleiden and Schwann, which confirmed that cell is the elementary unit of life. In the history, several researchers have worked to find answer to the central question of this science i.e. - ‘What is a cell and what is it good for?’
According to Schultze, cell is ‘a clump of protoplasm containing a nucleus’, the worlds of endocellular and ultrastructural organization. In 1950s and 60s, the studies further discovered the ‘compartimentalisation’ of the cell and this ‘compartimentalisation’ became roadmap for biochemical and molecular research.
The first cells were observed in plants. However, No data available as to who was the first scientist that described or theorised cell. Actually, the first structures which were called ‘cells’ were not cells as we know them today. Rather, they were cell walls enclosing empty holes or spaces filled with juices.
The development of Cell Biology begins with the advent of microscopy. English scientist Robert Hooke for the first time described ‘microscopical pores’ which he had observed in petrified wood in his work Micrographia (1664). But these cells were not cells; they were probably large or small vessels. He made the famous analogy in which he compared the structure of these vessels to a honeycomb, which has tiny boxes to monk cells. Independently, other microscopists made similar descriptions.
In 1672, Nehemiah Grew, English plant anatomist and physiologist, famously known as the Father of Plant Anatomy, wrote that the ‘Parenchyma’ (a term coined by himself) of the burdock flower consisted ‘a mass of bubbles’. After a decade later, he described them as ‘bladders’, ‘cells’ and ‘pores’ in his well known work- The Anatomy of Plants. In the same period, Italian physician Marcello Malpighi (1628–1694) mentioned ‘Utriculi’ and ‘Sacculi’ in plant tissues.
The first animal cells noted were single units such as blood corpuscles or spermatozoa. Several independent descriptions were made by Malpighi, Jan Swammerdam and Antoni van Leeuwenhoek of Netherlands, and others. Malpighi illustrated the presence of trachea and the ‘interlacement of utriculi’ in the tissue of the Oak tree. Swammerdam’s described the globular structures in various insect tissues. It was Johann Christian Wolff in his dissertation titled Theoria Generation declared that all development starts not with enfolded organs or miniature organisms but rather with an unformed mass of microscopic globules.
The first mention of ‘Cell’ in its singular meaning was made in 1792 by physiologist Stefano Gallini. Fifteen years later, German botanist Heinrich Friedrich Link identified a ‘double line’ separating neighbouring cells in the pith of the Devil’s Trumpet plant. In 1812, even more striking was Jakob Paul Moldenhawer’s empirical evidence; he cautiously pressed and macerated fresh plant tissues obtaining a series of single cells each enclosed by a proper membrane.
The merit of having discovered the cell nucleus is normally attributed to Robert Brown as he named it nucleus, though it was probably already seen by Leeuwenhoek, who in 1682 depicted a hollow ‘lumen’ in the red blood cells of fish. In 1781, Felice Fontana too noticed ‘little bodies’ inside tissue cells.
The Cell Theory of Schleiden and Schwann
The credit goes for botanist Matthias Jakob Schleiden and physiologist Theodor Schwann for having formulated the first cell theory. Indeed, as we have seen, they were neither the first ones to see or describe cells, nor to consider them vital units or the first stages of development. Still, the generalisations made by Schleiden in 1838, and most importantly the theory formulated by Schwann in 1839 represent the first synthetic cell theory in history and was soon accepted by their master Johannes Muller.
Still another student of Muller - the physician Rudolf Virchow deserves a special mention for advancing the unifying theory of cell reproduction and his famous aphorism Omnis cellula e cellula, which means – All cells come from existing cells. Ernst Wilhelm von Brucke described cells as the basis of physiological processes. In 1861, Carl Gegenbaur proclaimed that all types of eggs are egg cells; in 1863, Max Schultze recognized many microorganisms as unicellulars and Ernst Haeckel applied cell theory to zoological systems and Darwinism.
Schleiden and Schwann saw cells originating in a sort of spontaneous generation. According to them, within the amorphous ‘blastem’ granules gradually appear or crystallize, which aggregate to form the nucleolus and then the nucleus. Finally, the nucleus acts as ‘cytoblast’ and builds the cell which slowly puffs up ‘like the watch-glass on the watch’. When the process is completed, the nucleus has no further function and is often absorbed. Cytokinesis as the only process of the multiplication of cells was clearly stated in the 1840s mainly by Robert Remak (1815–1865) and John Goodsir (1814–1867), and definitely established by Rudolf Virchow.
Schleiden and Schwann characterized the cell as being constituted of ‘membrane, nucleus and mucus’. Since Hooke and Grew, it was known that many living cells contain some liquid substance. Cyclosis, the circulation of the cytoplasm within cells, has been accurately described and investigated by Italian botanist Bonaventura Corti in 1774.
In the first decades of the 19th century, several terms for this cellular liquid such as ‘jelly’, ‘sarcode’, 'parenchyma’ or ‘mucus’ were in circulation. In this period, the term ‘protoplasm’ introduced by Purkyne in 1839. However, he did not use it for all types of cells. This word became famous after it was reintroduced by botanist Hugo von Mohl in 1846 to name the viscous substance which ‘precedes the first solid structures’. Since 1861, cytoplasm definitely got a prominent role when Max Schultze and Franz von Leydig proposed their new definition of the cell as ‘a clump of protoplasm containing a nucleus’. Thomas Huxley’s famous proclamation i.e. protoplasm is to be considered the ‘physical basis of life’ marked the birth of Protoplasm Theory.
One of the most surprising discoveries was - abundance of membranes inside the cell. In 19th century, it became clear that the existing concepts of the nature of cell organelles had to be completely revised. Although Ernest Overton introduced three fundamental concepts of the structure and function of membranes in 1895, his contribution was appreciated only decades later. Here are the some of the most important discoveries - Plastids (‘Chloroplastiden’), which were first described by Friedrich Schmitz and Andreas Schimper in 1883; Mitochondria (‘Bioplasten’) by Richard Altmann in 1886; the Centrioles (‘dots’) by Edouard van Beneden and Theodor Boveri in 1887; the Endoplasmatic Reticulum (‘ergastoplasme’) by Charles Garnier in 1897 (though forgotten and rediscovered in 1945 by Keith Porter, Albert Claude and Ernest Fullam) and the Golgi Apparatus (‘apparato reticolare interno’) in 1898 by Camillo Golgi.
Chromosomes (‘transitorische Zytoblasten’) were probably first noticed in 1843 by Carl Wilhelm von Naegeli, and clearly described by Anton Schneider in 1873. In the rhabdocoel Mesostomum, Schneider depicted chromosomes (‘thick cords’) migrating to the two opposite poles. In the mid1870s, the elucidation of the process of mitosis found its first climax in the works of Eduard Strasburger and Walther Flemming, and in 1883 Edouard van Beneden gave a decisive contribution to enlighten the behaviour of chromosomes during meiosis. The last cytological treatise written by an individual author describing all the above mentioned discoveries was Edmund Beecher Wilson’s masterpiece The Cell in Development and Inheritance.
Albert Dalton and Marie Felix electron micrographs, for example, revealed that the Golgi apparatus was not made of rods, granules or a special ‘Golgi substance’, but rather made up of a pile of membranous compartments: flattened sacs, big vacuoles and small vesicles. Likewise, the studies mainly carried out by the two rival schools of George Palade of USA and of Fritiof Stig Sjöstrand of Sweden, transformed the mitochondria into complex systems of inner and outer membranes. In the 1960s, it was primarily the merit of biochemist Peter Mitchell (1920–1992) to have localized part of the pathway of oxidative phosphorylation in the membranes of the mitochondria, which were thus identified as the sites of cellular energetics.
Around 1950, Christian de Duve discovered the lysosomes, and shortly afterwards the peroxisomes, and linked them to cell metabolism. Contemporaneously, the steps of protein synthesis were clarified and conceptually connected to the fine structure of the endoplasmic reticulum and the ribosomes. These and other achievements significantly contributed to sketch a new general outline of cell structure and cell process and to mark the beginning of a new era of cytological research, that of Cell Biology.
Cell Biology, which started as fundamental study of Cells eventually expanded into other fields of biomedical inquiry.
According to Schultze, cell is ‘a clump of protoplasm containing a nucleus’, the worlds of endocellular and ultrastructural organization. In 1950s and 60s, the studies further discovered the ‘compartimentalisation’ of the cell and this ‘compartimentalisation’ became roadmap for biochemical and molecular research.
The first cells were observed in plants. However, No data available as to who was the first scientist that described or theorised cell. Actually, the first structures which were called ‘cells’ were not cells as we know them today. Rather, they were cell walls enclosing empty holes or spaces filled with juices.
The development of Cell Biology begins with the advent of microscopy. English scientist Robert Hooke for the first time described ‘microscopical pores’ which he had observed in petrified wood in his work Micrographia (1664). But these cells were not cells; they were probably large or small vessels. He made the famous analogy in which he compared the structure of these vessels to a honeycomb, which has tiny boxes to monk cells. Independently, other microscopists made similar descriptions.
In 1672, Nehemiah Grew, English plant anatomist and physiologist, famously known as the Father of Plant Anatomy, wrote that the ‘Parenchyma’ (a term coined by himself) of the burdock flower consisted ‘a mass of bubbles’. After a decade later, he described them as ‘bladders’, ‘cells’ and ‘pores’ in his well known work- The Anatomy of Plants. In the same period, Italian physician Marcello Malpighi (1628–1694) mentioned ‘Utriculi’ and ‘Sacculi’ in plant tissues.
The first animal cells noted were single units such as blood corpuscles or spermatozoa. Several independent descriptions were made by Malpighi, Jan Swammerdam and Antoni van Leeuwenhoek of Netherlands, and others. Malpighi illustrated the presence of trachea and the ‘interlacement of utriculi’ in the tissue of the Oak tree. Swammerdam’s described the globular structures in various insect tissues. It was Johann Christian Wolff in his dissertation titled Theoria Generation declared that all development starts not with enfolded organs or miniature organisms but rather with an unformed mass of microscopic globules.
The first mention of ‘Cell’ in its singular meaning was made in 1792 by physiologist Stefano Gallini. Fifteen years later, German botanist Heinrich Friedrich Link identified a ‘double line’ separating neighbouring cells in the pith of the Devil’s Trumpet plant. In 1812, even more striking was Jakob Paul Moldenhawer’s empirical evidence; he cautiously pressed and macerated fresh plant tissues obtaining a series of single cells each enclosed by a proper membrane.
The merit of having discovered the cell nucleus is normally attributed to Robert Brown as he named it nucleus, though it was probably already seen by Leeuwenhoek, who in 1682 depicted a hollow ‘lumen’ in the red blood cells of fish. In 1781, Felice Fontana too noticed ‘little bodies’ inside tissue cells.
The Cell Theory of Schleiden and Schwann
The credit goes for botanist Matthias Jakob Schleiden and physiologist Theodor Schwann for having formulated the first cell theory. Indeed, as we have seen, they were neither the first ones to see or describe cells, nor to consider them vital units or the first stages of development. Still, the generalisations made by Schleiden in 1838, and most importantly the theory formulated by Schwann in 1839 represent the first synthetic cell theory in history and was soon accepted by their master Johannes Muller.
Still another student of Muller - the physician Rudolf Virchow deserves a special mention for advancing the unifying theory of cell reproduction and his famous aphorism Omnis cellula e cellula, which means – All cells come from existing cells. Ernst Wilhelm von Brucke described cells as the basis of physiological processes. In 1861, Carl Gegenbaur proclaimed that all types of eggs are egg cells; in 1863, Max Schultze recognized many microorganisms as unicellulars and Ernst Haeckel applied cell theory to zoological systems and Darwinism.
Schleiden and Schwann saw cells originating in a sort of spontaneous generation. According to them, within the amorphous ‘blastem’ granules gradually appear or crystallize, which aggregate to form the nucleolus and then the nucleus. Finally, the nucleus acts as ‘cytoblast’ and builds the cell which slowly puffs up ‘like the watch-glass on the watch’. When the process is completed, the nucleus has no further function and is often absorbed. Cytokinesis as the only process of the multiplication of cells was clearly stated in the 1840s mainly by Robert Remak (1815–1865) and John Goodsir (1814–1867), and definitely established by Rudolf Virchow.
Schleiden and Schwann characterized the cell as being constituted of ‘membrane, nucleus and mucus’. Since Hooke and Grew, it was known that many living cells contain some liquid substance. Cyclosis, the circulation of the cytoplasm within cells, has been accurately described and investigated by Italian botanist Bonaventura Corti in 1774.
In the first decades of the 19th century, several terms for this cellular liquid such as ‘jelly’, ‘sarcode’, 'parenchyma’ or ‘mucus’ were in circulation. In this period, the term ‘protoplasm’ introduced by Purkyne in 1839. However, he did not use it for all types of cells. This word became famous after it was reintroduced by botanist Hugo von Mohl in 1846 to name the viscous substance which ‘precedes the first solid structures’. Since 1861, cytoplasm definitely got a prominent role when Max Schultze and Franz von Leydig proposed their new definition of the cell as ‘a clump of protoplasm containing a nucleus’. Thomas Huxley’s famous proclamation i.e. protoplasm is to be considered the ‘physical basis of life’ marked the birth of Protoplasm Theory.
One of the most surprising discoveries was - abundance of membranes inside the cell. In 19th century, it became clear that the existing concepts of the nature of cell organelles had to be completely revised. Although Ernest Overton introduced three fundamental concepts of the structure and function of membranes in 1895, his contribution was appreciated only decades later. Here are the some of the most important discoveries - Plastids (‘Chloroplastiden’), which were first described by Friedrich Schmitz and Andreas Schimper in 1883; Mitochondria (‘Bioplasten’) by Richard Altmann in 1886; the Centrioles (‘dots’) by Edouard van Beneden and Theodor Boveri in 1887; the Endoplasmatic Reticulum (‘ergastoplasme’) by Charles Garnier in 1897 (though forgotten and rediscovered in 1945 by Keith Porter, Albert Claude and Ernest Fullam) and the Golgi Apparatus (‘apparato reticolare interno’) in 1898 by Camillo Golgi.
Chromosomes (‘transitorische Zytoblasten’) were probably first noticed in 1843 by Carl Wilhelm von Naegeli, and clearly described by Anton Schneider in 1873. In the rhabdocoel Mesostomum, Schneider depicted chromosomes (‘thick cords’) migrating to the two opposite poles. In the mid1870s, the elucidation of the process of mitosis found its first climax in the works of Eduard Strasburger and Walther Flemming, and in 1883 Edouard van Beneden gave a decisive contribution to enlighten the behaviour of chromosomes during meiosis. The last cytological treatise written by an individual author describing all the above mentioned discoveries was Edmund Beecher Wilson’s masterpiece The Cell in Development and Inheritance.
Albert Dalton and Marie Felix electron micrographs, for example, revealed that the Golgi apparatus was not made of rods, granules or a special ‘Golgi substance’, but rather made up of a pile of membranous compartments: flattened sacs, big vacuoles and small vesicles. Likewise, the studies mainly carried out by the two rival schools of George Palade of USA and of Fritiof Stig Sjöstrand of Sweden, transformed the mitochondria into complex systems of inner and outer membranes. In the 1960s, it was primarily the merit of biochemist Peter Mitchell (1920–1992) to have localized part of the pathway of oxidative phosphorylation in the membranes of the mitochondria, which were thus identified as the sites of cellular energetics.
Around 1950, Christian de Duve discovered the lysosomes, and shortly afterwards the peroxisomes, and linked them to cell metabolism. Contemporaneously, the steps of protein synthesis were clarified and conceptually connected to the fine structure of the endoplasmic reticulum and the ribosomes. These and other achievements significantly contributed to sketch a new general outline of cell structure and cell process and to mark the beginning of a new era of cytological research, that of Cell Biology.
Cell Biology, which started as fundamental study of Cells eventually expanded into other fields of biomedical inquiry.
Published date : 10 May 2014 02:06PM
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