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Serous Gland
Serous glands secrete serous fluid. They contain serous acini, a grouping of serous cells that secrete serous fluid, isotonic with blood plasma, that contains enzymes such as alpha-amylase. Serous glands are most common in the parotid gland and lacrimal gland but are also present in the submandibular gland and, to a far lesser extent, the sublingual gland. Structure Serous acinar cells Serous acinar cells are the primary secretory cells of serous glands. They have a characteristic pyramidal shape, with a broad base that rests on the basement membrane and a narrow apex that faces the lumen of the acinus. These cells typically form spherical or tubular structures called acini (singular: acinus), which are the basic functional units of exocrine glands. Histologically, serous acinar cells exhibit: * A round, basally located nucleus * Extensive rough endoplasmic reticulum in the basal cytoplasm, giving it a basophilic appearance in H&E stains * Numerous secretory granules ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rabbit
Rabbits are small mammals in the family Leporidae (which also includes the hares), which is in the order Lagomorpha (which also includes pikas). They are familiar throughout the world as a small herbivore, a prey animal, a domesticated form of livestock, and a pet, having a widespread effect on ecologies and cultures. The most widespread rabbit genera are '' Oryctolagus'' and '' Sylvilagus''. The former, ''Oryctolagus'', includes the European rabbit, ''Oryctolagus cuniculus'', which is the ancestor of the hundreds of breeds of domestic rabbit and has been introduced on every continent except Antarctica. The latter, ''Sylvilagus'', includes over 13 wild rabbit species, among them the cottontails and tapetis. Wild rabbits not included in ''Oryctolagus'' and ''Sylvilagus'' include several species of limited distribution, including the pygmy rabbit, volcano rabbit, and Sumatran striped rabbit. Rabbits are a paraphyletic grouping, and do not constitute a clade, as ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parotid Gland
The parotid gland is a major salivary gland in many animals. In humans, the two parotid glands are present on either side of the mouth and in front of both ears. They are the largest of the salivary glands. Each parotid is wrapped around the mandibular ramus, and secretes serous saliva through the parotid duct into the mouth, to facilitate mastication and swallowing and to begin the digestion of starches. There are also two other types of salivary glands; they are submandibular and sublingual glands. Sometimes accessory parotid glands are found close to the main parotid glands. The venom glands of snakes are a modification of the parotid salivary glands. Etymology The word ''parotid'' literally means "beside the ear". From Greek παρωτίς (stem παρωτιδ-) : (gland) behind the ear < παρά - pará : in front, and οὖς - ous (stem ὠτ-, ōt-) : ear. Structure The parotid glands are a pair of mainly[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zymogen Granule
In biochemistry, a zymogen (), also called a proenzyme (), is an inactive precursor of an enzyme. A zymogen requires a biochemical change (such as a hydrolysis reaction revealing the active site, or changing the configuration to reveal the active site) to become an active enzyme. The biochemical change usually occurs in Golgi bodies, where a specific part of the precursor enzyme is cleaved in order to activate it. The inactivating piece which is cleaved off can be a peptide unit, or can be independently-folding domains comprising more than 100 residues. Although they limit the enzyme's ability, these N-terminal extensions of the enzyme or a "prosegment" often aid in the stabilization and folding of the enzyme they inhibit. The pancreas secretes zymogens partly to prevent the enzymes from digesting proteins in the cells where they are synthesised. Enzymes like pepsin are created in the form of pepsinogen, an inactive zymogen. Pepsinogen is activated when chief cells relea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acinus
An acinus (; : acini; adjective, acinar or acinous) refers to any cluster of cells that resembles a many-lobed "berry", such as a raspberry ('' acinus'' is Latin for "berry"). The berry-shaped termination of an exocrine gland, where the secretion is produced, is acinar in form, as is the alveolar sac containing multiple alveoli in the lungs. Exocrine glands Acinar exocrine glands are found in many organs, including: * the stomach * the sebaceous gland of the scalp * the salivary glands of the tongue * the liver * the lacrimal glands * the mammary glands * the pancreas * the bulbourethral (Cowper's) glands The thyroid follicles can also be considered of acinar formation but in this case the follicles, being part of an ''endocrine'' gland, act as a hormonal deposit rather than to facilitate secretion. Mucous acini usually stain pale, while serous acini usually stain dark. Lungs The end of the terminal bronchioles in the lungs The lungs are the primary organs of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exocrine Gland
Exocrine glands are glands that secrete substances onto an epithelial surface by way of a duct. Examples of exocrine glands include sweat, salivary, mammary, ceruminous, lacrimal, sebaceous, prostate and mucous. Exocrine glands are one of two types of glands in the human body, the other being endocrine glands, which secrete their products directly into the bloodstream. The liver and pancreas are both exocrine and endocrine glands; they are exocrine glands because they secrete products—bile and pancreatic juice—into the gastrointestinal tract through a series of ducts, and endocrine because they secrete other substances directly into the bloodstream. Exocrine sweat glands are part of the integumentary system; they have eccrine and apocrine types. Classification Structure Exocrine glands contain a glandular portion and a duct portion, the structures of which can be used to classify the gland. * The duct portion may be branched (called compound) or unbranched (called sim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acinic Cell Carcinoma
Acinic cell carcinoma is a malignant epithelial neoplasm that shows differentiation toward serous acinar cells of salivary gland origin. First described by Godwin et al. in 1954, it represents approximately 6-15% of all salivary gland malignancies, making it the third most common after mucoepidermoid carcinoma and adenoid cystic carcinoma. Approximately 80-90% of acinic cell carcinomas arise in the parotid gland, with the remainder occurring in the submandibular gland and minor salivary glands, particularly those of the buccal mucosa and palate. Rare cases have been reported in ectopic salivary gland tissue and in non-salivary sites including the breast, pancreas, and lung. Clinically, acinic cell carcinoma typically presents as a slow-growing, painless mass. The disease has a generally favorable prognosis, with 5-year survival rates exceeding 90% for localized disease, though recurrences can develop even decades after initial treatment. While traditionally considered a low-grade ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sublingual Gland
The sublingual gland (''glandula sublingualis'') is a seromucous polystomatic exocrine gland. Located underneath the oral diaphragm (''diaphragma oris''), the sublingual gland is the smallest and most diffuse of the three major salivary glands of the oral cavity, with the other two being the submandibular and parotid. The sublingual gland provides approximately 3-5% of the total salivary volume. Structure The submandibular glands are located anterior and superior to the submandibular gland and inferior and lateral to the tongue, as well as inferior to the mucous membrane of the floor of the mouth. They are bound laterally by the bone of the mandible and inferolaterally by the mylohyoid muscle. The glands can be palpated posteriorly to each mandibular canine. Placing one index finger within the mouth and the fingertips of the opposite hand outside it, the compressed gland is manually palpated between the inner and outer fingers.Illustrated Anatomy of the Head and Neck, Fehrenbac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Submandibular Gland
The paired submandibular glands (historically known as submaxillary glands) are major salivary glands located beneath the floor of the mouth. In adult humans, they each weigh about 15 grams and contribute some 60–67% of unstimulated saliva secretion; on stimulation their contribution decreases in proportion as parotid gland secretion rises to 50%. The average length of the normal adult human submandibular salivary gland is approximately 27 mm, while the average width is approximately 14.3 mm. Structure Each submandibular gland is divided into a superficial lobe and a deep lobe, the two being separated by the mylohyoid muscle: * The superficial lobe comprises most of the gland, with the mylohyoid muscle runs under it * The deep lobe is the smaller part Submandibular duct Secretions are delivered into the submandibular duct on the deep portion after which they hook around the posterior edge of the mylohyoid muscle and proceed on the superior surface laterally. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lacrimal Gland
The lacrimal glands are paired exocrine glands, one for each eye, found in most terrestrial vertebrates and some marine mammals, that secrete the aqueous layer of the tear film. In humans, they are situated in the upper lateral region of each orbit, in the lacrimal fossa of the orbit formed by the frontal bone. Inflammation of the lacrimal glands is called dacryoadenitis. The lacrimal gland produces tears which are secreted by the lacrimal ducts, and flow over the ocular surface, and then into canals that connect to the lacrimal sac. From that sac, the tears drain through the lacrimal duct into the nose. Anatomists divide the gland into two sections, a palpebral lobe, or portion, and an orbital lobe or portion. The smaller ''palpebral lobe'' lies close to the eye, along the inner surface of the eyelid; if the upper eyelid is everted, the palpebral portion can be seen. The orbital lobe of the gland, contains fine interlobular ducts that connect the orbital lobe and the palpe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Submaxillary Gland
The paired submandibular glands (historically known as submaxillary glands) are major salivary glands located beneath the floor of the mouth. In adult humans, they each weigh about 15 grams and contribute some 60–67% of unstimulated saliva secretion; on stimulation their contribution decreases in proportion as parotid gland secretion rises to 50%. The average length of the normal adult human submandibular salivary gland is approximately 27 mm, while the average width is approximately 14.3 mm. Structure Each submandibular gland is divided into a superficial lobe and a deep lobe, the two being separated by the mylohyoid muscle: * The superficial lobe comprises most of the gland, with the mylohyoid muscle runs under it * The deep lobe is the smaller part Submandibular duct Secretions are delivered into the submandibular duct on the deep portion after which they hook around the posterior edge of the mylohyoid muscle and proceed on the superior surface laterally. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzyme
An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecules known as product (chemistry), products. Almost all metabolism, metabolic processes in the cell (biology), cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme, pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts include Ribozyme, catalytic RNA molecules, also called ribozymes. They are sometimes descr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
