China
Africa
Explore chapters and articles related to this topic
The Nineteenth Century
Published in Scott M. Jackson, Skin Disease and the History of Dermatology, 2023
The nature and purpose of the cell, first discovered by Robert Hooke (1635–1703) in 1665, was not explained until 1839 when German botanist Matthias Schleiden (1804–1881) and his physiologist colleague Theodor Schwann (1810–1882) published the following principle: all living organisms consist of either a single cell or are made up of cells, the basic units of life. And thus, the era of cell theory began. Cell theory brought the study of anatomy, physiology, and pathology from a macroscopic, fluid-based (humor-based) or even organ-based level to a microscopic one. It was only a matter of time before the physicians and scientists of the nineteenth theory could no longer rectify Galenic theory with the discoveries of the period.
Introduction to Cells, DNA, and Viruses
Published in Patricia G. Melloy, Viruses and Society, 2023
Before learning about viruses, it is useful to understand what they infect: our cells. It has been known for quite some time that our bodies are made of cells. Going back to the early 1800s, Matthias Schleiden and Theodor Schwann determined that all animals and plants are made of cells. Cells are defined philosophically as being the fundamental units of life and are distinctive for being able to reproduce themselves to make other cells. All these ideas (animals and plants are made of cells, cells are the fundamental units of life, cells give rise to other cells) put together became what is now called the cell theory (Alberts et al. 2019). From the point of view of chemical content, one can also define cells as containing many macromolecules needed for the processes of life, protected by the cell membrane. Although our cells are mostly made of water, the key macromolecules present are critical for cellular function, including nucleic acids, carbohydrates, proteins, and lipids. DNA and ribonucleic acids (RNA) are nucleic acids, made of building blocks called nucleotides. Proteins are made of amino acids. Carbohydrates are made of sugar subunits. Lipids, also known as fats, are made of fatty acids and glycerol. See Table 1.1 for key definitions.
The Nature and Cause of Cancer: Historical Overview
Published in Jeremy R. Jass, Understanding Pathology, 2020
Theodor Schwann (1810–1882) established the universal cell theory in 1839: the cell unit comprised a nucleus and surrounding cell sap enclosed by a wall. The cell sap was found to be contractile and glutinous, and was described as protoplasm (now known as cytoplasm) by Jan Purkinje (1787–1869). It was originally held that cells formed like crystals but in a biological medium called ‘cytoblastema’. Microscopic techniques aided the recognition of replication of cells by division into two identical ‘daughter’ cells a number of years later. Walther Flemming (1843–1905) recognised the separation of chromosomes during cell division, introducing the term ‘mitosis’ to describe this process. Rudolf Virchow (1821–1902) was the first to appreciate that cancer was a disease of cells that grew through the process of cell division, but believed that cancers arose from ‘embryonic’ or primitive cells scattered throughout the connective tissue of the body. It was Wilhelm Waldeyer (1837–1921) who argued for the origin of cancers from the tissues with which they were associated, cancers of skin arising from the epithelium of the skin itself and cancers of the epithelium lining hollow organs arising from the same.
Neuroanniversary 2021
Published in Journal of the History of the Neurosciences, 2021
Rudolf Ludwig Carl Virchow (1821–1902; see Figure 2) was a German physician, anthropologist, pathologist, prehistorian, biologist, writer, editor, and politician. Known as the father of modern pathology, he studied medicine at the Friedrich-Wilhelms Institute under Johannes Peter Müller (1801–1858) and worked at the Charité hospital under Robert Froriep (1804–1861), whom he succeeded as prosector. A prolific writer, his scientific writings alone exceeded 2000 publications. Cellular Pathology (1858), regarded as the root of modern pathology, introduced the third dictum in cell theory: Omnis cellula e cellula [All cells come from cells]. Virchow was the first to describe and name diseases such as leukemia, chordoma, ochronosis, embolism, and thrombosis. He coined biological terms such as chromatin, neuroglia, agenesis, parenchyma, osteoid, amyloid degeneration, and spina bifida; terms such as Virchow’s node, Virchow–Robin spaces, Virchow–Seckel syndrome, and Virchow’s triad are named after him.
Microscopic anatomy of sensory receptors
Published in Journal of the History of the Neurosciences, 2019
The microscopic world was transformed by the introduction of powerful achromatic instruments in the 1830s, and rapid advances were made thereafter (Finger, 1994; Harris, 1999; Schickore, 2001, 2007). Among those who combined the achromatic microscope with remarkable observational skills was Jan Purkinje (or Purkyně; 1787–1869; 1837; see Figure 1). In 1832, Purkinje obtained an achromatic microscope manufactured by Simon Plössl (1794–1868) in Vienna (Chvátal, 2017) and directed it at the large cells in the cerebellum, thereby identifying the cells that bear his name. His microscopic observations were made before any adequate staining methods had been developed. Purkinje used alcohol to fix his preparations, and he made thin sections so they could be examined microscopically. Purkinje’s laboratory at Breslau (present-day Wroclaw) has been described as the cradle of histology, and it was matched only by that in Berlin (Otis, 2007), established by Johannes Müller (1801–1858). Cell theory was most clearly articulated by Matthias Schleiden (1804–1881; 1838) for plants and Theodor Schwann (1810–1882; 1839) for animals, and it is associated with their names. At the end of the century, Wilhelm von Waldeyer (1836–1921; 1891) extended the doctrine to nerves. He named the nerve cell body, its fibers, and arborizations as a “neurone” and supported the doctrine that neurons were the fundamental structural and functional units of the nervous system (see Shepherd, 1991).
Relationship of Posterior Capsular Opacification and Capsular Bend Type Investigation Based on Swept-source Optical Coherence Tomography
Published in Current Eye Research, 2020
Yu Fang, Ding Xixia, Li Jin, Lin Lei, Chang Pingjun, Zhang Hongfang, Zhao Yun-e
Classical no space no cell theory has been suggested. Previous studies indicate that tight adhesion between the posterior capsular bag and IOL plays a key role in PCO prevention.25–28 However, in this study, we found there was no statistical difference in PCO score and area between the eyes with complete and incomplete adhesion of posterior capsule and IOL. And, a complete overlap of the capsulorhexis margin with the IOL optic is likely to be an important factor in the postoperative prevention of PCO, which is in agreement with previous studies.17,18,29,30 In the total overlap group, a large proportion of PCO occurred in the haptic area. Meanwhile, in the partial overlap group, almost 80% of the eyes had PCO in the haptic or detached area.