Antonie Philips van Leeuwenhoek[note 2] FRS (/ˈɑːntəni vɑːn ˈleɪvənhʊk/ AHN-tə-nee vahn LAY-vən-huuk, Dutch: [ɑnˈtoːni vɑn ˈleːuə(n)ˌɦuk] (listen); 24 October 1632 – 26 August 1723) was a Dutch businessman and scientist in the Golden Age of Dutch science and technology. A largely self-taught man in science, he is commonly known as "the Father of Microbiology", and one of the first microscopists and microbiologists. Van Leeuwenhoek is best known for his pioneering work in microscopy and for his contributions toward the establishment of microbiology as a scientific discipline.
Raised in Delft, Dutch Republic, van Leeuwenhoek worked as a draper in his youth and founded his own shop in 1654. He became well recognized in municipal politics and developed an interest in lensmaking. In the 1670s, he started to explore microbial life with his microscope.[note 3] This was one of the notable achievements of the Golden Age of Dutch exploration and discovery (c. 1590s–1720s).
Using single-lensed microscopes of his own design, van Leeuwenhoek was the first to experiment with microbes, which he originally referred to as animalcules (from Latin animalculum = "tiny animal"). Through his experiments, he was the first to relatively determine their size. Most of the "animalcules" are now referred to as unicellular organisms, although he observed multicellular organisms in pond water. He was also the first to document microscopic observations of muscle fibers, bacteria, spermatozoa, red blood cells, crystals in gouty tophi, and blood flow in capillaries. Although van Leeuwenhoek did not write any books, his discoveries came to light through correspondence with the Royal Society, which published his letters.
Antonie van Leeuwenhoek
A portrait of Antonie van Leeuwenhoek (1632–1723) by Jan Verkolje
|Born||24 October 1632|
|Died||26 August 1723 (aged 90)|
Delft, Dutch Republic
|Known for||The first acknowledged microscopist and microbiologist[note 1]|
Microscopic discovery of microorganisms (animalcule)
Regnier de Graaf
|Influenced||History of biology and life sciences|
Age of Reason
Antonie van Leeuwenhoek was born in Delft, Dutch Republic, on 24 October 1632. On 4 November, he was baptized as Thonis. His father, Philips Antonisz van Leeuwenhoek, was a basket maker who died when Antonie was only five years old. His mother, Margaretha (Bel van den Berch), came from a well-to-do brewer's family. She remarried Jacob Jansz Molijn, a painter. Antonie had four older sisters: Margriet, Geertruyt, Neeltje, and Catharina. When he was around ten years old his step-father died. He attended school in Warmond for a short time before being sent to live in Benthuizen with his uncle, an attorney. At the age of 16 he became a bookkeeper's apprentice at a linen-draper's shop in Amsterdam, which was owned by the Scot William Davidson. Van Leeuwenhoek left there after six years.
Van Leeuwenhoek married Barbara de Mey in July 1654, with whom he fathered one surviving daughter, Maria (four other children died in infancy). That same year he returned to Delft, where he would live and study for the rest of his life. He opened a draper's shop, which he ran throughout the 1650s. His wife died in 1666, and in 1671, Van Leeuwenhoek remarried to Cornelia Swalmius with whom he had no children. His status in Delft had grown throughout the years. In 1660 he received a lucrative job as chamberlain for the assembly chamber of the Delft sheriffs in the city hall, a position which he would hold for almost 40 years. In 1669 he was appointed as a land surveyor by the court of Holland; at some time he combined it with another municipal job, being the official "wine-gauger" of Delft and in charge of the city wine imports and taxation.
Van Leeuwenhoek was a contemporary of another famous Delft citizen, the painter Johannes Vermeer, who was baptized just four days earlier. It has been suggested that he is the man portrayed in two Vermeer paintings of the late 1660s, The Astronomer and The Geographer, but others argue that there appears to be little physical similarity. Because they were both relatively important men in a city with only 24,000 inhabitants, it is likely that they were at least acquaintances; Van Leeuwenhoek acted as the executor of Vermeer's will after the painter died in 1675.[note 4]
While running his draper shop, van Leeuwenhoek wanted to see the quality of the thread better than what was possible using the magnifying lenses of the time. He developed an interest in lensmaking, although few records exist of his early activity. Van Leeuwenhoek's interest in microscopes and a familiarity with glass processing led to one of the most significant, and simultaneously well-hidden, technical insights in the history of science.
By placing the middle of a small rod of soda lime glass in a hot flame, van Leeuwenhoek could pull the hot section apart to create two long whiskers of glass. Then, by reinserting the end of one whisker into the flame, he could create a very small, high-quality glass sphere. These spheres became the lenses of his microscopes, with the smallest spheres providing the highest magnifications.
After developing his method for creating powerful lenses and applying them to the study of the microscopic world, van Leeuwenhoek introduced his work to his friend, the prominent Dutch physician Reinier de Graaf. When the Royal Society in London published the groundbreaking work of an Italian lensmaker in their journal Philosophical Transactions of the Royal Society, de Graaf wrote to the editor of the journal, Henry Oldenburg, with a ringing endorsement of van Leeuwenhoek's microscopes which, he claimed, "far surpass those which we have hitherto seen". In response, in 1673 the society published a letter from van Leeuwenhoek that included his microscopic observations on mold, bees, and lice.
Van Leeuwenhoek's work fully captured the attention of the Royal Society, and he began corresponding regularly with the society regarding his observations. At first he had been reluctant to publicize his findings, regarding himself as a businessman with little scientific, artistic, or writing background, but de Graaf urged him to be more confident in his work. By the time van Leeuwenhoek died in 1723, he had written some 190 letters to the Royal Society, detailing his findings in a wide variety of fields, centered on his work in microscopy. He only wrote letters in his own colloquial Dutch; he never published a proper scientific paper in Latin. He strongly preferred to work alone, distrusting the sincerity of those who offered their assistance. The letters were translated into Latin or English by Henry Oldenburg, who had learned Dutch for this very purpose. Despite the initial success of van Leeuwenhoek's relationship with the Royal Society, soon relations became severely strained. In 1676, his credibility was questioned when he sent the Royal Society a copy of his first observations of microscopic single-celled organisms. Previously, the existence of single-celled organisms was entirely unknown. Thus, even with his established reputation with the Royal Society as a reliable observer, his observations of microscopic life were initially met with some skepticism.
Eventually, in the face of van Leeuwenhoek's insistence, the Royal Society arranged for Alexander Petrie, minister to the English Reformed Church in Delft; Benedict Haan, at that time Lutheran minister at Delft; and Henrik Cordes, then Lutheran minister at the Hague, accompanied by Sir Robert Gordon and four others, to determine whether it was in fact van Leeuwenhoek's ability to observe and reason clearly, or perhaps, the Royal Society's theories of life that might require reform. Finally in 1677, van Leeuwenhoek's observations were fully acknowledged by the Royal Society.
Antonie van Leeuwenhoek was elected to the Royal Society in February 1680 on the nomination of William Croone, a then-prominent physician.[note 5] Van Leeuwenhoek was "taken aback" by the nomination, which he considered a high honor, although he did not attend the induction ceremony in London, nor did he ever attend a Royal Society meeting.
By the end of the seventeenth century, van Leeuwenhoek had a virtual monopoly on microscopic study and discovery. His contemporary Robert Hooke, an early microscope pioneer, bemoaned that the field had come to rest entirely on one man's shoulders. He was visited over the years by many notable individuals, such as the Russian Tsar Peter the Great. To the disappointment of his guests, van Leeuwenhoek refused to reveal the cutting-edge microscopes he relied on for his discoveries, instead showing visitors a collection of average-quality lenses.
An experienced businessman, van Leeuwenhoek believed that if his simple method for creating the critically important lens was revealed, the scientific community of his time would likely disregard or even forget his role in microscopy. He therefore allowed others to believe that he was laboriously spending most of his nights and free time grinding increasingly tiny lenses to use in microscopes, even though this belief conflicted both with his construction of hundreds of microscopes and his habit of building a new microscope whenever he chanced upon an interesting specimen that he wanted to preserve. He made about 200 microscopes with a different magnification.
Van Leeuwenhoek was visited by Leibniz, William III of Orange and his wife, Mary II of England, and the burgemeester (mayor) Johan Huydecoper of Amsterdam, the latter being very interested in collecting and growing plants for the Hortus Botanicus Amsterdam, and all gazed at the tiny creatures. In 1698, van Leeuwenhoek was invited to visit the Tsar Peter the Great on his boat. On this occasion van Leeuwenhoek presented the Tsar an "eel-viewer", so Peter could study blood circulation whenever he wanted.
Antonie van Leeuwenhoek made more than 500 optical lenses. He also created at least 25 single-lens microscopes, of differing types, of which only nine have survived. These microscopes were made of silver or copper frames, holding hand-made lenses. Those that have survived are capable of magnification up to 275 times. It is suspected that van Leeuwenhoek possessed some microscopes that could magnify up to 500 times. Although he has been widely regarded as a dilettante or amateur, his scientific research was of remarkably high quality.
The single-lens microscopes of van Leeuwenhoek were relatively small devices, the largest being about 5 cm long. They are used by placing the lens very close in front of the eye, while looking in the direction of the sun. The other side of the microscope had a pin, where the sample was attached in order to stay close to the lens. There were also three screws to move the pin and the sample along three axes: one axis to change the focus, and the two other axes to navigate through the sample.
Van Leeuwenhoek maintained throughout his life that there are aspects of microscope construction "which I only keep for myself", in particular his most critical secret of how he made the lenses. For many years no one was able to reconstruct van Leeuwenhoek's design techniques, but in 1957, C.L. Stong used thin glass thread fusing instead of polishing, and successfully created some working samples of a van Leeuwenhoek design microscope. Such a method was also discovered independently by A. Mosolov and A. Belkin at the Russian Novosibirsk State Medical Institute.
Van Leeuwenhoek used samples and measurements to estimate numbers of microorganisms in units of water. He also made good use of the huge advantage provided by his method. He studied a broad range of microscopic phenomena, and shared the resulting observations freely with groups such as the British Royal Society. Such work firmly established his place in history as one of the first and most important explorers of the microscopic world. Van Leeuwenhoek was one of the first people to observe cells, much like Robert Hooke.
Van Leeuwenhoek's main discoveries are:
In 1687, van Leeuwenhoek reported his research on the coffee bean. He roasted the bean, cut it into slices and saw a spongy interior. The bean was pressed, and an oil appeared. He boiled the coffee with rain water twice and set it aside.
Van Leeuwenhoek's religion was "Dutch Reformed" Calvinist. He often referred with reverence to the wonders God designed in making creatures great and small, and believed that his discoveries were merely further proof of the wonder of creation.
By the end of his life, van Leeuwenhoek had written approximately 560 letters to the Royal Society and other scientific institutions concerning his observations and discoveries. Even during the last weeks of his life, van Leeuwenhoek continued to send letters full of observations to London. The last few contained a precise description of his own illness. He suffered from a rare disease, an uncontrolled movement of the midriff, which now is named van Leeuwenhoek's disease. He died at the age of 90, on 26 August 1723, and was buried four days later in the Oude Kerk in Delft.
In 1981, the British microscopist Brian J. Ford found that van Leeuwenhoek's original specimens had survived in the collections of the Royal Society of London. They were found to be of high quality, and all were well preserved. Ford carried out observations with a range of single-lens microscopes, adding to our knowledge of van Leeuwenhoek's work. In Ford's opinion, Leeuwenhoek remained imperfectly understood, the popular view that his work was crude and undisciplined at odds with the evidence of conscientious and painstaking observation. He constructed rational and repeatable experimental procedures and was willing to oppose received opinion, such as spontaneous generation, and he changed his mind in the light of evidence.
On his importance in the history of microbiology and science in general, the British biochemist Nick Lane wrote that he was "the first even to think of looking—certainly, the first with the power to see." His experiments were ingenious and he was "a scientist of the highest calibre", attacked by people who envied him or "scorned his unschooled origins", not helped by his secrecy about his methods.
The Antoni van Leeuwenhoek Hospital in Amsterdam, named after van Leeuwenhoek, is specialized in oncology. In 2004, a public poll in the Netherlands to determine the greatest Dutchman ("De Grootste Nederlander") named van Leeuwenhoek the 4th-greatest Dutchman of all time.
The Leeuwenhoek Medal, Leeuwenhoek Lecture, Leeuwenhoek (crater), Leeuwenhoeckia, Levenhookia (a genus in the family Stylidiaceae), and Leeuwenhoekiella (an aerobic bacterial genus) are named after him.
Indeed, in this publication "Geneeskundig Verhaal van de Algemeene Loop-ziekte..." [Valk (1745)], the author uses the work of Leeuwenhoek in describing the disease, draws some (preliminary) conclusions about the cause of the disease, he warns "non-believers of Van Leeuwenhoek to use a magnifying glass" and gives commentaries on the work of Anthonie van Leeuwenhoek and his findings.
Animalcule ("little animal", from Latin animal + the diminutive suffix -culum) is an older term for a microscopic animal or protozoan. The concept appears to have been proposed at least as early as c. 30 BC, as evidenced by the following translation from Marcus Varro's Rerum Rusticarum Libri Tres:
'Note also if there be any swampy ground, both for the reasons given above, and because certain minute animals, invisible to the eye, breed there, and, borne by the air, reach the inside of the body by way of the mouth and nose, and cause diseases which are difficult to be rid of.'Some better-known animalcules include:
Actinophrys, and other heliozoa, called sun animalcules
Amoeba, called Proteus animalcule
Noctiluca scintillans, commonly called the 'Sea Sparkles'
Paramecium, called slipper animalcules
Rotifers, called wheel animalcules
Stentor, called trumpet animalcules
Vorticella, and other peritrichs, called bell animalculesThe term was also used by Anton van Leeuwenhoek, the 17th-century preformationist and the discoverer of microorganisms, to describe them.The word appears in adjectival form in the Major-General's Song, in which Major-General Stanley sings, "I know the scientific names of beings animalculous..."Antonie van Leeuwenhoek (journal)
Antonie van Leeuwenhoek is a peer-reviewed scientific journal covering microbiology published by Springer Science+Business Media. The journal was established in 1934 and is published monthly. The editor-in-chief is Iain Sutcliffe. The journal is named after Antonie van Leeuwenhoek, considered the father of microbiology.Ciliate
The ciliates are a group of protozoans characterized by the presence of hair-like organelles called cilia, which are identical in structure to eukaryotic flagella, but are in general shorter and present in much larger numbers, with a different undulating pattern than flagella. Cilia occur in all members of the group (although the peculiar Suctoria only have them for part of their life-cycle) and are variously used in swimming, crawling, attachment, feeding, and sensation.
Ciliates are an important group of protists, common almost anywhere there is water — in lakes, ponds, oceans, rivers, and soils. About 3,500 species have been described, and the potential number of extant species is estimated at 30,000. Included in this number are many ectosymbiotic and endosymbiotic species, as well as some obligate and opportunistic parasites. Ciliate species range in size from as little as 10 µm to as much as 4 mm in length, and include some of the most morphologically complex protozoans.In most systems of taxonomy, "Ciliophora" is ranked as a phylum, under either the kingdom Protista or Protozoa. In some systems of classification, ciliated protozoa are placed within the class "Ciliata," (a term which can also refer to a genus of fish). In the taxonomic scheme proposed by the International Society of Protistologists, which eliminates formal rank designations such as "phylum" and "class", "Ciliophora" is an unranked taxon within Alveolata.Delft
Delft ([dɛlft] (listen)) is a city and municipality in the province of South Holland, Netherlands. It is located between Rotterdam, to the southeast, and The Hague, to the northwest. Together with them, it is part of both Rotterdam–The Hague metropolitan area and the Randstad.
Delft is a popular tourist attraction in the country. It is home to Delft University of Technology (TU Delft), regarded as center of technological research and development in the Netherlands, Delft Blue pottery and the currently reigning House of Orange-Nassau. Historically, Delft played a highly influential role in the Dutch Golden Age. Delft has a special place in the history of microbiology. In terms of science and technology, thanks to the pioneering contributions of Antonie van Leeuwenhoek and Martinus Beijerinck, Delft can be considered to be the true birthplace of microbiology, with its several sub-disciplines such as bacteriology, protozoology, and virology.Eimeria stiedae
Eimeria stiedae is a species of Eimeria that causes hepatic coccidiosis in rabbits. It was observed for the first time by Antonie van Leeuwenhoek in 1674.Giardia
Giardia ( or ) is a genus of anaerobic flagellated protozoan parasites of the phylum metamonada that colonise and reproduce in the small intestines of several vertebrates, causing giardiasis. Their life cycle alternates between a swimming trophozoite and an infective, resistant cyst. Giardia were first described by the Dutch microscopist Antonie van Leeuwenhoek in 1681. The genus is named after French zoologist Alfred Mathieu Giard.Infusoria
Infusoria is a collective term for minute aquatic creatures such as ciliates, euglenoids, protozoa, unicellular algae and small invertebrates that exist in freshwater ponds. Some authors (e.g., Bütschli) used the term as a synonym for Ciliophora. In modern formal classifications, the term is considered obsolete; the microorganisms previously included in the Infusoria are mostly assigned to the kingdom Protista. Researchers have proposed that infusoria reproductive rates periodically increase and decrease over periods of time.Leeuwenhoek (crater)
Leeuwenhoek is a lunar impact crater that lies in the Moon's southern hemisphere, on the far side from the Earth. It is located to the east of the crater Birkeland and the unusual double crater Van de Graaff. To the northeast of Leeuwenhoek is Orlov and to the south is the large walled plain Leibnitz.
The outer rim of Leeuwenhoek is worn and eroded, forming an irregular mountainous ring about the relatively level interior floor. The inner wall is wider along the western and southern sides, offseting the floor to the northeast. At the midpoint of the interior is a central peak formation. There are a pair of small craterlets on the floor and several tiny craters. Leeuwenhoek partly overlaps the satellite crater Leeuwenhoek E to the northeast.Leeuwenhoek Lecture
The Leeuwenhoek Lecture is a prize lecture of the Royal Society to recognize achievement in microbiology. The prize was originally given in 1950 and awarded annually. From 2006 to 2018 the prize was given triannually. Since 2018 the prize is awarded biannually. It is named after the Dutch microscopist Anton van Leeuwenhoek and was instituted in 1948 from a bequest from George Gabb. A gift of £2000 is associated with the lecture.Leeuwenhoek Medal
The Leeuwenhoek Medal, established in 1877 by the Royal Netherlands Academy of Arts and Sciences, (KNAW), in honor of the 17th- and 18th-century microscopist Antoni van Leeuwenhoek, is granted every ten years to the scientist judged to have made the most significant contribution to microbiology during the preceding decade. From 2015 the Royal Dutch Society for Microbiology (KNVM) will be awarding the Leeuwenhoek Medal.List of microscopists
This is a list a microscopists.Microbiology
Microbiology (from Greek μῑκρος, mīkros, "small"; βίος, bios, "life"; and -λογία, -logia) is the study of microorganisms, those being unicellular (single cell), multicellular (cell colony), or acellular (lacking cells). Microbiology encompasses numerous sub-disciplines including virology, parasitology, mycology and bacteriology.
Eukaryotic microorganisms possess membrane-bound cell organelles and include fungi and protists, whereas prokaryotic organisms—all of which are microorganisms—are conventionally classified as lacking membrane-bound organelles and include Bacteria and Archaea. Microbiologists traditionally relied on culture, staining, and microscopy. However, less than 1% of the microorganisms present in common environments can be cultured in isolation using current means. Microbiologists often rely on molecular biology tools such as DNA sequence based identification, for example 16s rRNA gene sequence used for bacteria identification.
Viruses have been variably classified as organisms, as they have been considered either as very simple microorganisms or very complex molecules. Prions, never considered as microorganisms, have been investigated by virologists, however, as the clinical effects traced to them were originally presumed due to chronic viral infections, and virologists took search—discovering "infectious proteins".
The existence of microorganisms was predicted many centuries before they were first observed, for example by the Jains in India and by Marcus Terentius Varro in ancient Rome. The first recorded microscope observation was of the fruiting bodies of moulds, by Robert Hooke in 1666, but the Jesuit priest Athanasius Kircher was likely the first to see microbes, which he mentioned observing in milk and putrid material in 1658. Antonie van Leeuwenhoek is considered a father of microbiology as he observed and experimented with microscopic organisms in 1676, using simple microscopes of his own design. Scientific microbiology developed in the 19th century through the work of Louis Pasteur and in medical microbiology Robert Koch.Non-motile bacteria
Non-motile bacteria are those bacterial species that lack the ability and structures that would allow them to propel themselves, under their own power, through their environment. When non-motile bacteria are cultured in a stab tube, they only grow along the stab line. If the bacteria are mobile, the line will appear diffuse and extend into the medium. The cell structures that provide the ability for locomotion are the cilia and flagella. Coliform and Streptococci are examples of non-motile bacteria as are Klebsiella pneumoniae, and Yersinia pestis. Motility is one characteristic used in the identification of bacteria and evidence of possessing structures: peritrichous flagella, polar flagella and/or a combination of both.Though the lack of motility might be regarded a disadvantage, some non-motile bacteria possess structures that allow their attachment to eukaryotic cells, like GI mucousal cells.Vancomycin resistant Enterococcus spp. are non-motile while vancomycin susceptible Enterococcus spp. Some genera have been divided based upon the presence or absence of motility. Motility is determined by using a motility medium. The ingredients include motility test medium, nutrient broth powder, NaCl and distilled water. An inoculating needle (not a loop) is used to insert the bacterial sample. The needle is inserted through the medium for a length of one inch. The media tube incubated at 380C. Bacteria that are motile grow away from the stab, and toward the sides and downward toward the bottom of the tube. Growth should be observed in 24 to 48 hours. With some species, the bacterium is inconsistent related to its motility.Peter Sneath
Peter Henry Andrews Sneath FRS, MD (17 November 1923 – September 9, 2011) was a microbiologist who co-founded the field of numerical taxonomy, together with Robert R. Sokal. Sneath and Sokal wrote Principles of Numerical Taxonomy, revised in 1973 as Numerical Taxonomy. Sneath reviewed the state of numerical taxonomy in 1995 and wrote some autobiographical notes in 2010.A special issue of the journal Antonie van Leeuwenhoek, on microbial systematics, is dedicated to the memory of Peter Sneath.Protozoa
Protozoa (also protozoan, plural protozoans) is an informal term for single-celled eukaryotes, either free-living or parasitic, which feed on organic matter such as other microorganisms or organic tissues and debris. Historically, the protozoa were regarded as "one-celled animals", because they often possess animal-like behaviors, such as motility and predation, and lack a cell wall, as found in plants and many algae. Although the traditional practice of grouping protozoa with animals is no longer considered valid, the term continues to be used in a loose way to identify single-celled organisms that can move independently and feed by heterotrophy.
In some systems of biological classification, Protozoa is a high-level taxonomic group. When first introduced in 1818, Protozoa was erected as a taxonomic class, but in later classification schemes it was elevated to a variety of higher ranks, including phylum, subkingdom and kingdom. In a series of classifications proposed by Thomas Cavalier-Smith and his collaborators since 1981, Protozoa has been ranked as a kingdom. The seven-kingdom scheme presented by Ruggiero et al. in 2015, places eight phyla under Kingdom Protozoa: Euglenozoa, Amoebozoa, Metamonada, Choanozoa sensu Cavalier-Smith, Loukozoa, Percolozoa, Microsporidia and Sulcozoa. Notably, this kingdom excludes several major groups of organisms traditionally placed among the protozoa, including the ciliates, dinoflagellates, foraminifera, and the parasitic apicomplexans, all of which are classified under Kingdom Chromista. Kingdom Protozoa, as defined in this scheme, does not form a natural group or clade, but a paraphyletic group or evolutionary grade, within which the members of Fungi, Animalia and Chromista are thought to have evolved.Rotifer
The rotifers (Rotifera, commonly called wheel animals) make up a phylum of microscopic and near-microscopic pseudocoelomate animals.
They were first described by Rev. John Harris in 1696, and other forms were described by Antonie van Leeuwenhoek in 1703. Most rotifers are around 0.1–0.5 mm long (although their size can range from 50 μm to over 2 mm), and are common in freshwater environments throughout the world with a few saltwater species.
Some rotifers are free swimming and truly planktonic, others move by inchworming along a substrate, and some are sessile, living inside tubes or gelatinous holdfasts that are attached to a substrate. About 25 species are colonial (e.g., Sinantherina semibullata), either sessile or planktonic. Rotifers are an important part of the freshwater zooplankton, being a major foodsource and with many species also contributing to the decomposition of soil organic matter. Most species of the rotifers are cosmopolitan, but there are also some endemic species, like Cephalodella vittata to Lake Baikal. Recent barcoding evidence, however, suggests that some 'cosmopolitan' species, such as Brachionus plicatilis, B. calyciflorus, Lecane bulla, among others, are actually species complexes.In some recent treatments, rotifers are placed with acanthocephalans in a larger clade called Syndermata.Spermatozoon
A spermatozoon (pronounced , alternate spelling spermatozoön; plural spermatozoa; from Ancient Greek: σπέρμα "seed" and Ancient Greek: ζῷον "living being") is a motile sperm cell, or moving form of the haploid cell that is the male gamete. A spermatozoon joins an ovum to form a zygote. (A zygote is a single cell, with a complete set of chromosomes, that normally develops into an embryo.)
Sperm cells contribute approximately half of the nuclear genetic information to the diploid offspring (excluding, in most cases, mitochondrial DNA). In mammals, the sex of the offspring is determined by the sperm cell: a spermatozoon bearing a X chromosome will lead to a female (XX) offspring, while one bearing a Y chromosome will lead to a male (XY) offspring. Sperm cells were first observed in Anton van Leeuwenhoek's laboratory in 1677.Spermine
Spermine is a polyamine involved in cellular metabolism found in all eukaryotic cells. The precursor for synthesis of spermine is the amino acid ornithine. It is found in a wide variety of organisms and tissues and is an essential growth factor in some bacteria. It is found as a polycation at physiological pH. Spermine is associated with nucleic acids and is thought to stabilize helical structure, particularly in viruses.
Crystals of spermine phosphate were first described in 1678, in human semen, by Antonie van Leeuwenhoek. The name spermin was first used by the German chemists Ladenburg and Abel in 1888, and the correct structure of spermine was not finally established until 1926, simultaneously in England (by Dudley, Rosenheim, and Starling) and Germany (by Wrede et al.). Spermine is the chemical primarily responsible for the characteristic odor of semen.Volvox
Volvox is a polyphyletic genus of chlorophyte green algae in the family Volvocaceae. It forms spherical colonies of up to 50,000 cells. They live in a variety of freshwater habitats, and were first reported by Antonie van Leeuwenhoek in 1700. Volvox diverged from unicellular ancestors approximately 200 million years ago.
Antonie van Leeuwenhoek
|Microscopic discoveries 1|