Camillo Golgi Biography Where was Golgi born? in the village of Corteno, Did Golgi complete any military service? worked as a civil physician in the Italian Army, Who was Golgi's most important teacher? I don't know.
Did Golgi marry?
Did Camillo Golgi marry?
Camillo Golgi was born in July 1843 in the village of Corteno, in the province of Brescia (Lombardy), Italy. The village is now named Corteno Golgi in his honour. His father Allessandro Golgi was a physician and district medical officer, originally from Pavia. In 1860, he entered the University of Pavia to study medicine, and earned his medical degree in 1865. He did an internship at the San Matteo Hospital (now IRCCS Policlinico San Matteo Foundation). During his internship he briefly worked as a civil physician in the Italian Army, and as assistant surgeon at the Novara Hospital (now Azienda Ospedaliero Universitaria Maggiore della Carita di Novara). At the same time he was also involved in the medical team for investigating cholera epidemic in villages around Pavia.  In 1867, he resumed his academic study under the supervision of Cesare Lombroso. Lombroso was a renowned scientist in medical psychology such as genius, madness and criminality. Inspired by Lombroso, Golgi wrote a thesis on the etiology of mental disorders, from which he obtained his M.D. in 1868. He became more interested in experimental medicine, and started attending the Institute of General Pathology headed by Giulio Bizzozero. Three years his junior, Bizzozero was an eloquent teacher and experimenter, who specialised in histology of the nervous system and the properties of bone marrow. The most important research publications of Golgi were directly or indirectly influenced by Bizzozero. The two became so close that they lived in the same building; and Golgi later married Bizzozero's niece, Lina Aletti. By 1872, Golgi was an established clinician and histopathologist. He, however, had no opportunity as a tenured professor in Pavia to pursue teaching and research in neurology.  Financial pressure prompted him to join the Hospital of the Chronically Ill (Pio Luogo degli Incurabili) in Abbiategrasso, near Milan, as Chief Medical Officer in 1872. To continue research, he set up a simple laboratory on his own in a refurbished hospital kitchen, and it was there that he started making his most notable discoveries. His major achievement was the development of staining technique for nerve tissue called the black reaction (later the Golgi's method). He published his major works between 1875 and 1885 in the journal Rivista sperimentale di Freniatria e di medicina legale. In 1785, he joined the faculty of histology at the University of Pavia. In 1879, he was appointed Chair of Anatomy at the University of Siena. But the next year, he returned to the University of Pavia as full Professor of histology. From 1879 he also became Professor of General Pathology as well as Honorary Chief (Primario ad honorarem) at the San Matteo Hospital. He served as Rector of the University of Pavia twice, first between 1893 and 1896, and second between 1901 and 1909. During the First World War (1914-1917), he directed the military hospital Collegio Borrmeo at Pavia. He retired in 1918 and continued to research in his private laboratory till 1923. He died on 21 January 1926. CANNOTANSWER
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Camillo Golgi (; 7 July 184321 January 1926) was an Italian biologist and pathologist known for his works on the central nervous system. He studied medicine at the University of Pavia (where he later spent most of his professional career) between 1860 and 1868 under the tutelage of Cesare Lombroso. Inspired by pathologist Giulio Bizzozero, he pursued research in the nervous system. His discovery of a staining technique called black reaction (sometimes called Golgi's method or Golgi's staining in his honour) in 1873 was a major breakthrough in neuroscience. Several structures and phenomena in anatomy and physiology are named for him, including the Golgi apparatus, the Golgi tendon organ and the Golgi tendon reflex.

Golgi and the Spanish biologist Santiago Ramón y Cajal were jointly given the Nobel Prize in Physiology or Medicine 1906 "in recognition of their work on the structure of the nervous system".

Biography
Camillo Golgi was born on 7 July 1843 in the village of Corteno near Brescia, in the province of Brescia (Lombardy), at the time Kingdom of Lombardy–Venetia, today Italy. The village is now named Corteno Golgi in his honour. His father Alessandro Golgi was a physician and district medical officer, originally from Pavia. In 1860, he entered the University of Pavia to study medicine, and earned his medical degree in 1865. He did an internship at the San Matteo Hospital (now IRCCS Policlinico San Matteo Foundation). During his internship he briefly worked as a civil physician in the Italian Army, and as assistant surgeon at the Novara Hospital (now Azienda Ospedaliero Universitaria Maggiore della Carità di Novara). At the same time he was also involved in the medical team for investigating cholera epidemic in villages around Pavia.

In 1867, he resumed his academic study under the supervision of Cesare Lombroso. Lombroso was a renowned scientist in medical psychology such as genius, madness and criminality. Inspired by Lombroso, Golgi wrote a thesis on the etiology of mental disorders, from which he obtained his M.D. in 1868. He became more interested in experimental medicine, and started attending the Institute of General Pathology headed by Giulio Bizzozero. Three years his junior, Bizzozero was an eloquent teacher and experimenter, who specialised in histology of the nervous system and the properties of bone marrow. The most important research publications of Golgi were directly or indirectly influenced by Bizzozero. The two became so close that they lived in the same building; and Golgi later married Bizzozero's niece, Lina Aletti. By 1872, Golgi was an established clinician and histopathologist. He, however, had no opportunity as a tenured professor in Pavia to pursue teaching and research in neurology.

Financial pressure prompted him to join the Hospital of the Chronically Ill (Pio Luogo degli Incurabili) in Abbiategrasso, near Milan, as Chief Medical Officer in 1872. To continue research, he set up a simple laboratory on his own in a refurbished hospital kitchen, and it was there that he started making his most notable discoveries. His major achievement was the development of staining technique for nerve tissue called the black reaction (later the Golgi's method). He published his major works between 1875 and 1885 in the journal Rivista sperimentale di Freniatria e di medicina legale. In 1875, he joined the faculty of histology at the University of Pavia. In 1879, he was appointed Chair of Anatomy at the University of Siena. But the next year, he returned to the University of Pavia as full Professor of histology. From 1879 he also became Professor of General Pathology as well as Honorary Chief (Primario ad honorarem) at the San Matteo Hospital. He served as Rector of the University of Pavia twice, first between 1893 and 1896, and second between 1901 and 1909. During the First World War (1914–1917), he directed the military hospital Collegio Borrmeo at Pavia. He retired in 1918 and continued to research in his private laboratory till 1923. He died on 21 January 1926.

Personal life

Golgi and his wife Lina Aletti had no children, and they adopted Golgi's niece Carolina.

Golgi was irreligious in his later life and became an agnostic atheist. One of his former students attempted an unsuccessful deathbed conversion on him.

Contributions

Black reaction or Golgi's staining

The Central nervous system was difficult to study during Golgi's time because the cells were hard to identify. The available tissue staining techniques were useless for studying nervous tissue. While working as chief medical officer at the Hospital of the Chronically Ill, he experimented with metal impregnation of nervous tissue, using mainly silver (silver staining). In early 1873, he discovered a method of staining nervous tissue that would stain a limited number of cells at random in their entirety. He first treated the tissue with potassium dichromate to harden it, and then with silver nitrate. Under the microscope, the outline of the neuron became distinct from the surrounding tissue and cells. The silver chromate precipitate, as a reaction product, selectively stains only some cellular components randomly, sparing other cell parts. The silver chromate particles create a stark black deposit on the soma (nerve cell body) as well as on the axon and all dendrites, providing an exceedingly clear and well-contrasted picture of neuron against a yellow background. This makes it easier to trace the structure of the nerve cells in the brain for the first time. Since cells are selective stained in black, he called the process la reazione nera ("the black reaction"), but today it is called Golgi's method or the Golgi stain. On 16 February 1873, he wrote to his friend Niccolò Manfredi:

His discovery was published in the Gazzeta Medica Italiani on 2 August 1873.

Nervous system

In 1871, a German anatomist Joseph von Gerlach postulated that the brain is a complex "protoplasmic network", in the form of a continuous network called the reticulum. Using his black reaction, Golgi could trace various regions of the cerebro-spinal axis, clearly distinguishing the different nervous projections, namely axon from the dendrites. He drew up a new classification of cells on the basis of the structure of their nervous prolongation. He described an extremely dense and intricate network, composed of a web of intertwined branches of axons coming from different cell layers ("diffuse nervous network"). This network structure, which emerges from the axons, is essentially different from that hypothesized by Gerlach. It was the main organ of the central nervous system according to Golgi. Thus, Golgi presented the reticular theory which states that the brain is a single network of nerve fibres, and not of discrete cells. Although Golgi's earlier works between 1873 and 1885 clearly depicted the axonal connections of cerebellar cortex and olfactory bulb as independent of one another, his later works including the Nobel Lecture showed the entire granular layer of the cerebellar cortex occupied by a network of branching and anastomosing nerve processes. This was due to his strong conviction in the reticular theory. Golgi's theory was challenged by Ramón y Cajal, who used the same technique developed by Golgi. According to Ramón y Cajal's neurone theory, the nervous system is but a collection of individual cells, the neurones, which are interconnected to form a network.

In addition to this, Golgi was the first to give clear descriptions of the structure of the cerebellum, hippocampus, spinal cord, olfactory lobe, as well as striatal and cortical lesions in a case of chorea. In 1878, he also discovered a receptor organ that senses changes in muscle tension, and is now known as Golgi tendon organ or Golgi receptor; and Golgi-Mazzoni corpuscles (pressure transductors). He further developed a stain specific for myelin (a specialised membrane which wraps around the axon) using potassium dichromate and mercuric chloride. Using this he discovered the myelin annular apparatus, often called the horny funnel of Golgi-Rezzonico.

Kidney
Golgi studied kidney function during 1882 to 1889. In 1882, he published his observations on the mechanism of renal hypertrophy, which he understood to be due to renal cell proliferation. In 1884, he described tubular cell mitoses in the kidney of a person suffering from tubulointerstitial nephritis, and he noted that the process was an essential part of repairing the kidney tissue. He was the first to dissect out intact nephrons, and show that the distal tubulus (loop of Henle) of the nephron returns to its originating glomerulus, a finding that he published in 1889 ("Annotazioni intorno all'Istologia dei reni dell'uomo e di altri mammifieri e sull'istogenesi dei canalicoli oriniferi". Rendiconti R. Acad. Lincei 5: 545–557, 1889).

Malaria
A French Army physician Charles Louis Alphonse Laveran discovered that malaria was caused by microscopic parasite (now called Plasmodium falciparum) in 1880. But scientists were sceptical until Golgi intervened. It was Golgi who helped him prove that malarial parasite was a microscopic protozoan. From 1885, Golgi studied the malarial parasite and its transmission. He established two types of malaria, tertian and quartan fevers caused by Plasmodium vivax and Plasmodium malariae respectively. In 1886, he discovered that malarial fever (paroxysm) was produced by the asexual stage in the human blood (called erythocytic cycle, or Golgi cycle). In 1889–1890, Golgi and Ettore Marchiafava described the differences between benign tertian malaria and malignant tertian malaria (the latter caused by P. falciparum). By 1898, along with Giovanni Battista Grassi, Amico Bignami, Giuseppe Bastianelli, Angelo Celli and Marchiafava, he confirmed that malaria was transmitted by Anopheline mosquito.

Cell organelle

An organelle in eukaryotice cells now known as Golgi apparatus or Golgi complex, or sometimes simply as Golgi, was discovered by Camillo Golgi. Golgi modified his black reaction using osmium dichromate solution with which he stained the nerve cells (Purkinje cells) of the cerebellum of an owl. He noticed thread-like networks inside the cells and named them apparato reticolare interno (internal reticular apparatus). Recognising them to be unique cellular components, he presented his discovery before the Medical-Surgical Society of Pavia in April 1898. After the same was confirmed by his assistant Emilio Veratti, he published it in the Bollettino della Società medico-chirurgica di Pavia. However, most scientists disputed his discovery as nothing but a staining artefact. Their microscopes were not powerful enough to identify the organelles. By the 1930s, Golgi's description was largely rejected. It was only firmly established 50 years after its discovery, when electron microscopes were developed.

Awards and legacy
Golgi, together with Santiago Ramón y Cajal, received the Nobel Prize in Physiology or Medicine in 1906 for his studies of the structure of the nervous system. In 1900 he was named senator by King Umberto I. In 1913 he became foreign member of the Royal Netherlands Academy of Arts and Sciences. He received honorary doctorates from the University of Cambridge, University of Geneva, Kristiania University College, National and Kapodistrian University of Athens, and Paris-Sorbonne University. In 1994, the European Community commemorated him with postage stamps.

Monuments in Pavia  

In Pavia several landmarks stand as Golgi's memory.
 A marble statue, in a yard of the old buildings of the University of Pavia, at N.65 of the central "Strada Nuova". On the basement, there is the following inscription in Italian language: "Camillo Golgi / patologo sommo / della scienza istologica / antesignano e maestro / la segreta struttura / del tessuto nervoso / con intenta vigilia / sorprese e descrisse / qui operò / qui vive / guida e luce ai venturi / MDCCCXLIII – MCMXXVI" (Camillo Golgi / outstanding pathologist / of histological science / precursor and master / the secret structure / of the nervous tissue / with strenuous effort / discovered and described / here he worked / here he lives / here he guides and enlightens future scholars / 1843 – 1926).
 "Golgi’s home", also in Strada Nuova, at N.77, a few hundreds meters away from the University, just in front to the historical "Teatro Fraschini". It is the home in which Golgi spent the most of his family life, with his wife Lina.
 Golgi's tomb is in the Monumental Cemetery of Pavia (viale San Giovannino), along the central lane, just before the big monument to the fallen of the First World War. It is a very simple granite grave, with a bronze medallion representing the scientist's profile. Near Golgi's tomb, apart from his wife, two other important Italian medical scientists are buried: Bartolomeo Panizza  and Adelchi Negri.
 Golgi's museum was created in 2012, in the ancient Palazzo Botta of the University of Pavia at N.10 of Piazza Antoniotto Botta reconstructs the study of Camillo Golgi and its laboratories with furniture and original instruments.

Eponyms
 The organelle Golgi apparatus or Golgi complex
 The sensory receptor Golgi tendon organ
 Golgi's method or Golgi stain, a nervous tissue staining technique
 The enzyme Golgi alpha-mannosidase II
 Golgi cells of the cerebellum
 Golgi I nerve cells (with long axons)
 Golgi II nerve cells (with short or no axons)
 Golgi (crater), a lunar impact crater 
 Minor planet 6875 Golgi is named after him.

See also
 List of pathologists

References

Further reading

External links 
 Life and Discoveries of Camillo Golgi
  including the Nobel Lecture on 11 December 1906 The Neuron Doctrine – Theory and Facts
 Some places and memories related to Camillo Golgi
 The museum in Corteno, now called Corteno Golgi, dedicated to Golgi. Includes a gallery of images of his birthplace.
 The Museum Camillo Golgi in Pavia
 Biography at Encyclopædia Britannica
 Biography at Encyclopedia.com
 Profile at Whonamedit?
 IRCCS Policlinico San Matteo Foundation
 Azienda Ospedaliero Universitaria Maggiore della Carità di Novara

1843 births
1926 deaths
University of Pavia alumni
People from the Province of Brescia
Physicians from Pavia
Italian agnostics
Italian neuroscientists
Italian anatomists
Italian pathologists
History of neuroscience
Nobel laureates in Physiology or Medicine
Italian Nobel laureates
Corresponding members of the Saint Petersburg Academy of Sciences
Recipients of the Pour le Mérite (civil class)
Malariologists
Members of the Royal Netherlands Academy of Arts and Sciences
Members of the Senate of the Kingdom of Italy
Golgi may refer to:
Camillo Golgi (1843–1926), Italian physician and scientist after whom the following terms are named: 
Golgi apparatus (also called the Golgi body, Golgi complex, or dictyosome), an organelle in a eukaryotic cell
Golgi tendon organ, a proprioceptive sensory receptor organ
Golgi's method or Golgi stain, a nervous tissue staining technique
Golgi alpha-mannosidase II, an enzyme
Golgi cell, a type of interneuron found in the cerebellum
Golgi I, a nerve cell with a long axon
Golgi II, a nerve cell with a short or no axon
Golgi (crater), a lunar impact crater
Córteno Golgi, an Italian village The Golgi apparatus (), also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic cells. Part of the endomembrane system in the cytoplasm, it packages proteins into membrane-bound vesicles inside the cell before the vesicles are sent to their destination. It resides at the intersection of the secretory, lysosomal, and endocytic pathways. It is of particular importance in processing proteins for secretion, containing a set of glycosylation enzymes that attach various sugar monomers to proteins as the proteins move through the apparatus.

It was identified in 1897 by the Italian scientist Camillo Golgi and was named after him in 1898.

Discovery
Owing to its large size and distinctive structure, the Golgi apparatus was one of the first organelles to be discovered and observed in detail. It was discovered in 1898 by Italian physician Camillo Golgi during an investigation of the nervous system. After first observing it under his microscope, he termed the structure as apparato reticolare interno ("internal reticular apparatus"). Some doubted the discovery at first, arguing that the appearance of the structure was merely an optical illusion created by the observation technique used by Golgi. With the development of modern microscopes in the twentieth century, the discovery was confirmed. Early references to the Golgi apparatus referred to it by various names including the "Golgi–Holmgren apparatus", "Golgi–Holmgren ducts", and "Golgi–Kopsch apparatus". The term "Golgi apparatus" was used in 1910 and first appeared in the scientific literature in 1913, while "Golgi complex" was introduced in 1956.

Subcellular localization

The subcellular localization of the Golgi apparatus varies among eukaryotes. In mammals, a single Golgi apparatus is usually located near the cell nucleus, close to the centrosome. Tubular connections are responsible for linking the stacks together. Localization and tubular connections of the Golgi apparatus are dependent on microtubules. In experiments it is seen that as microtubules are depolymerized the Golgi apparatuses lose mutual connections and become individual stacks throughout the cytoplasm. In yeast, multiple Golgi apparatuses are scattered throughout the cytoplasm (as observed in Saccharomyces cerevisiae). In plants, Golgi stacks are not concentrated at the centrosomal region and do not form Golgi ribbons. Organization of the plant Golgi depends on actin cables and not microtubules. The common feature among Golgi is that they are adjacent to endoplasmic reticulum (ER) exit sites.

Structure 

In most eukaryotes, the Golgi apparatus is made up of a series of compartments and is a collection of fused, flattened membrane-enclosed disks known as cisternae (singular: cisterna, also called "dictyosomes"), originating from vesicular clusters that bud off the endoplasmic reticulum. A mammalian cell typically contains 40 to 100 stacks of cisternae. Between four and eight cisternae are usually present in a stack; however, in some protists as many as sixty cisternae have been observed. This collection of cisternae is broken down into cis, medial, and trans compartments, making up two main networks: the cis Golgi network (CGN) and the trans Golgi network (TGN). The CGN is the first cisternal structure, and the TGN is the final, from which proteins are packaged into vesicles destined to lysosomes, secretory vesicles, or the cell surface. The TGN is usually positioned adjacent to the stack, but can also be separate from it. The TGN may act as an early endosome in yeast and plants.

There are structural and organizational differences in the Golgi apparatus among eukaryotes. In some yeasts, Golgi stacking is not observed. Pichia pastoris does have stacked Golgi, while Saccharomyces cerevisiae does not. In plants, the individual stacks of the Golgi apparatus seem to operate independently.

The Golgi apparatus tends to be larger and more numerous in cells that synthesize and secrete large amounts of substances; for example, the antibody-secreting plasma B cells of the immune system have prominent Golgi complexes.

In all eukaryotes, each cisternal stack has a cis entry face and a trans exit face. These faces are characterized by unique morphology and biochemistry. Within individual stacks are assortments of enzymes responsible for selectively modifying protein cargo. These modifications influence the fate of the protein. The compartmentalization of the Golgi apparatus is advantageous for separating enzymes, thereby maintaining consecutive and selective processing steps: enzymes catalyzing early modifications are gathered in the cis face cisternae, and enzymes catalyzing later modifications are found in trans face cisternae of the Golgi stacks.

Function 

The Golgi apparatus is a major collection and dispatch station of protein products received from the endoplasmic reticulum (ER). Proteins synthesized in the ER are packaged into vesicles, which then fuse with the Golgi apparatus. These cargo proteins are modified and destined for secretion via exocytosis or for use in the cell. 
In this respect, the Golgi can be thought of as similar to a post office: it packages and labels items which it then sends to different parts of the cell or to the extracellular space. The Golgi apparatus is also involved in lipid transport and lysosome formation.

The structure and function of the Golgi apparatus are intimately linked. Individual stacks have different assortments of enzymes, allowing for progressive processing of cargo proteins as they travel from the cisternae to the trans Golgi face. Enzymatic reactions within the Golgi stacks occur exclusively near its membrane surfaces, where enzymes are anchored. This feature is in contrast to the ER, which has soluble proteins and enzymes in its lumen. Much of the enzymatic processing is post-translational modification of proteins. For example, phosphorylation of oligosaccharides on lysosomal proteins occurs in the early CGN. Cis cisterna are associated with the removal of mannose residues. Removal of mannose residues and addition of N-acetylglucosamine occur in medial cisternae. Addition of galactose and sialic acid occurs in the trans cisternae. Sulfation of tyrosines and carbohydrates occurs within the TGN. Other general post-translational modifications of proteins include the addition of carbohydrates (glycosylation) and phosphates (phosphorylation). Protein modifications may form a signal sequence that determines the final destination of the protein. For example, the Golgi apparatus adds a mannose-6-phosphate label to proteins destined for lysosomes. Another important function of the Golgi apparatus is in the formation of proteoglycans. Enzymes in the Golgi append proteins to glycosaminoglycans, thus creating proteoglycans. Glycosaminoglycans are long unbranched polysaccharide molecules present in the extracellular matrix of animals.

Vesicular transport

The vesicles that leave the rough endoplasmic reticulum are transported to the cis face of the Golgi apparatus, where they fuse with the Golgi membrane and empty their contents into the lumen. Once inside the lumen, the molecules are modified, then sorted for transport to their next destinations.

Those proteins destined for areas of the cell other than either the endoplasmic reticulum or the Golgi apparatus are moved through the Golgi cisternae towards the trans face, to a complex network of membranes and associated vesicles known as the trans-Golgi network (TGN). This area of the Golgi is the point at which proteins are sorted and shipped to their intended destinations by their placement into one of at least three different types of vesicles, depending upon the signal sequence they carry.

Current models of vesicular transport and trafficking

Model 1: Anterograde vesicular transport between stable compartments
 In this model, the Golgi is viewed as a set of stable compartments that work together. Each compartment has a unique collection of enzymes that work to modify protein cargo. Proteins are delivered from the ER to the cis face using COPII-coated vesicles. Cargo then progress toward the trans face in COPI-coated vesicles. This model proposes that COPI vesicles move in two directions: anterograde vesicles carry secretory proteins, while retrograde vesicles recycle Golgi-specific trafficking proteins.
 Strengths: The model explains observations of compartments, polarized distribution of enzymes, and waves of moving vesicles. It also attempts to explain how Golgi-specific enzymes are recycled.
 Weaknesses: Since the amount of COPI vesicles varies drastically among types of cells, this model cannot easily explain high trafficking activity within the Golgi for both small and large cargoes. Additionally, there is no convincing evidence that COPI vesicles move in both the anterograde and retrograde directions.
 This model was widely accepted from the early 1980s until the late 1990s.

Model 2: Cisternal progression/maturation
 In this model, the fusion of COPII vesicles from the ER begins the formation of the first cis-cisterna of the Golgi stack, which progresses later to become mature TGN cisternae. Once matured, the TGN cisternae dissolve to become secretory vesicles. While this progression occurs, COPI vesicles continually recycle Golgi-specific proteins by delivery from older to younger cisternae. Different recycling patterns may account for the differing biochemistry throughout the Golgi stack. Thus, the compartments within the Golgi are seen as discrete kinetic stages of the maturing Golgi apparatus.
 Strengths: The model addresses the existence of Golgi compartments, as well as differing biochemistry within the cisternae, transport of large proteins, transient formation and disintegration of the cisternae, and retrograde mobility of native Golgi proteins, and it can account for the variability seen in the structures of the Golgi.
 Weaknesses: This model cannot easily explain the observation of fused Golgi networks, tubular connections among cisternae, and differing kinetics of secretory cargo exit.

Model 3: Cisternal progression/maturation with heterotypic tubular transport
 This model is an extension of the cisternal progression/maturation model. It incorporates the existence of tubular connections among the cisternae that form the Golgi ribbon, in which cisternae within a stack are linked. This model posits that the tubules are important for bidirectional traffic in the ER-Golgi system: they allow for fast anterograde traffic of small cargo and/or the retrograde traffic of native Golgi proteins.
 Strengths: This model encompasses the strengths of the cisternal progression/maturation model that also explains rapid trafficking of cargo, and how native Golgi proteins can recycle independently of COPI vesicles.
 Weaknesses: This model cannot explain the transport kinetics of large protein cargo, such as collagen. Additionally, tubular connections are not prevalent in plant cells. The roles that these connections have can be attributed to a cell-specific specialization rather than a universal trait. If the membranes are continuous, that suggests the existence of mechanisms that preserve the unique biochemical gradients observed throughout the Golgi apparatus.

Model 4: Rapid partitioning in a mixed Golgi
 This rapid partitioning model is the most drastic alteration of the traditional vesicular trafficking point of view. Proponents of this model hypothesize that the Golgi works as a single unit, containing domains that function separately in the processing and export of protein cargo. Cargo from the ER move between these two domains, and randomly exit from any level of the Golgi to their final location. This model is supported by the observation that cargo exits the Golgi in a pattern best described by exponential kinetics. The existence of domains is supported by fluorescence microscopy data.
 Strengths: Notably, this model explains the exponential kinetics of cargo exit of both large and small proteins, whereas other models cannot.
 Weaknesses: This model cannot explain the transport kinetics of large protein cargo, such as collagen. This model falls short on explaining the observation of discrete compartments and polarized biochemistry of the Golgi cisternae. It also does not explain formation and disintegration of the Golgi network, nor the role of COPI vesicles.

Model 5: Stable compartments as cisternal model progenitors
 This is the most recent model. In this model, the Golgi is seen as a collection of stable compartments defined by Rab (G-protein) GTPases.
 Strengths: This model is consistent with numerous observations and encompasses some of the strengths of the cisternal progression/maturation model. Additionally, what is known of the Rab GTPase roles in mammalian endosomes can help predict putative roles within the Golgi. This model is unique in that it can explain the observation of "megavesicle" transport intermediates.
 Weaknesses: This model does not explain morphological variations in the Golgi apparatus, nor define a role for COPI vesicles. This model does not apply well for plants, algae, and fungi in which individual Golgi stacks are observed (transfer of domains between stacks is not likely). Additionally, megavesicles are not established to be intra-Golgi transporters.

Though there are multiple models that attempt to explain vesicular traffic throughout the Golgi, no individual model can independently explain all observations of the Golgi apparatus. Currently, the cisternal progression/maturation model is the most accepted among scientists, accommodating many observations across eukaryotes. The other models are still important in framing questions and guiding future experimentation. Among the fundamental unanswered questions are the directionality of COPI vesicles and role of Rab GTPases in modulating protein cargo traffic.

Brefeldin A
Brefeldin A (BFA) is a fungal metabolite used experimentally to disrupt the secretion pathway as a method of testing Golgi function. BFA blocks the activation of some ADP-ribosylation factors (ARFs). ARFs are small GTPases which regulate vesicular trafficking through the binding of COPs to endosomes and the Golgi. BFA inhibits the function of several guanine nucleotide exchange factors (GEFs) that mediate GTP-binding of ARFs. Treatment of cells with BFA thus disrupts the secretion pathway, promoting disassembly of the Golgi apparatus and distributing Golgi proteins to the endosomes and ER.

Gallery

References

External links 

 

Organelles