Bird's anatomy , or the physiological structure of the bird's body, shows many unique adaptations, most of which help flight. Birds have a lightweight and lightweight frame system but strong muscles, along with circulatory and respiratory systems that are capable of having very high levels of metabolism and oxygen supply, allow birds to fly. The development of the beak has led to the evolution of specially tailored digestive systems. This anatomical specialization has received their own class bird in vertebrate phyla.
Video Bird anatomy
Sistem skeletal
Skeleton Aksial
The bird skeleton is highly customized for flight. It's very light but powerful enough to withstand the pressure of taking off, flying, and landing. One key adaptation is bone melting into a single ossification, such as pygostyle. Therefore, birds usually have bones smaller than other land vertebrates. Birds also lack teeth or even real jaw, instead of having a beak, which is much lighter. The beak of many baby birds has a projection called an egg tooth, which eases them out of the amniotic egg, and it falls as soon as it has done its job.
Vertebral column
The vertebral column is divided into five parts of the vertebra:
- Cervix (11-25) (neck)
- The vertebral (dorsal or thoracic) trunk usually fused in the notarium.
- Synsacrum (back fused vertebrae also blend with hips (pelvis)). This area is similar to the sacrum of mammals and unique in pigeons because it is a combination of sacral, lumbar and caudal vertebrae. It is attached to the pelvis and supports the terrestrial movement of the pigeon's foot.
- Caudal (5-10): This area is similar to the tail bone in mammals and helps control the movement of feathers during flight.
- Pygostyle (tails): This region consists of 4 to 7 united vertebrae and is the point of attachment of the feathers.
A bird's neck consists of 13-25 cervical vertebrae allowing birds to have increased flexibility. The flexible neck allows many birds with moving eyes to move their heads more productively and focus their views on objects that are near or far in the distance. Most birds have about three times more neck bones than humans that allow for increased stability during fast movements such as flying, landing, and taking off. The neck plays a role in head-bobbing which is present in at least 8 of the 27 bird orders, including Columbiformes, Galliformes, and Gruiformes. Head-bobbing is an optokinetic response that stabilizes the bird environment as they alternate between thrust phase and resistance phase. Head-bobbing is in sync with the feet as the head moves according to the rest of the body. Data from various studies indicate that the main reason for swinging in some birds is to stabilize their environment, although it is uncertain why some but not all bird orders show beahviors from head-bobbing. Birds are the only vertebrates that have collapsible collarbones and lymph nodes. The reinforced web serves as a place for the muscles used for flying or swimming. Unleavened birds, like ostriches, do not have thick bones and have bones that are denser and heavier than flying birds. Swimmers have wide breasts, running birds have long breastbones, and birds have chest bones that are almost as wide and high.
Birds bones are often less hollow than non-dive species. Penguins, bells and puffin without bone pneumatization completely. Flyless birds, such as ostriches and emus, show osseous pneumatics, have pneumatized femeur and, in the case of emu, cervical pneumatization vertebrae.
The chest consists of furcula (wishbone) and coracoid (neckbone), which, along with the scapula (see below), form a breast corset. The chest side is formed by ribs, which meet in the sternum (chest central line).
Iga
The birds have an irregular process in the ribs. This is a hinged bone extension that helps strengthen the ribs by overlapping with the ribs behind them. This feature is also found in tuatara ( Sphenodon ).
Birds have many hollow bones (pneumatization) with crossing struts or trunks for structural strength. The number of hollow bones varies among species, although large, flying and flying birds tend to have the most. The air sacs of breathing often form air pockets inside the semi-hollow bone of the bird bone.
Skull
The skull consists of five major bones: the frontal (top of the head), the parietal (back of the head), the premaxillary and the nose (the upper half), and the mandible (lower half). Normal bird skulls typically weigh about 1% of the total weight of birds. The eye occupies a large number of skulls and is surrounded by sclerotic rings, small bony rings. This characteristic is also seen in reptiles.
In general, the bird's skull consists of many small bones that do not overlap. Paedomorphosis, the preservation of ancestral states in adults, is thought to have facilitated the evolution of bird skulls. In essence, the skull of an adult bird will resemble the shape of the teenage ancestor of their theropod dinosaur. As the avian lineage has progressed and paedomorphosis has occurred, they have lost postorbital bones behind the eyes, ectopterygoid behind the ceiling, and teeth. The structure of the ceiling has also greatly changed with changes, mostly reductions, seen in ptyergoid, palatine, and jugal bones. Adductor space reductions have also occurred. These are all conditions seen in the form of their ancestors. Premaxillary bone has also undergone hypertrophy to form the beak while the maxilla has been reduced, as suggested by developmental and paleontologic studies. This expansion into the beak occurs simultaneously with the loss of functional hands and the development of a point on the front of the beak that resembles a "finger". Interestingly, premaxila is also known to play a major role in eating behavior in fish.
The structure of a bird's skull has important implications for their eating behavior. Birds show an independent movement of skull bones known as cranial kinesis. The cranial kinesis of the birds occurs in several forms, but all the different varieties are all made possible by the anatomy of the skull. Animals with large overlapping bones (including modern bird ancestors) have an akinetic (non-kinetic) skull (I.e.). For this reason it has been argued that the paedomorphic bird beak can be seen as an evolutionary innovation.
They have diapsid skulls, as in reptiles, with pre-lachrymal fossa (present in some reptiles). The skull has a single occipital condyle.
Appendicular Framework
Shoulders consist of scapula (shoulder blades), coracoid, and humerus (upper arms). Humerus joins the fingers and the ulna (forearm) to form the elbows. Carpus and metacarpus form the "wrist" and "hand" of the birds, and the figures are merged together. Bones in the wings are so light that birds can fly more easily.
The hip consists of the pelvis, which includes three major bones: the ilium (the top of the hip), the iscium (hip side), and the pubis (front of the hip). It blends into one (innominate bone). The innominate bone is a significant evolution as they allow birds to spawn. They meet on the acetabulum (hip socket) and articulate with the femur, which is the first bone of the hind legs.
The upper leg consists of the femur. In the knee joint, the femur is connected to the tibiotarsus (the shinbone) and the fibula (the lower leg side). The tarsometatarsus forms the upper part of the foot, the digit forming the toes. The bird's leg bone is the heaviest, contributing to the low center of gravity, which helps in flight. The bird skeleton only accounts for about 5% of the total body weight
They have a very elongated tetradiate pelvis, similar to some reptiles. The rear members have intra-tarsal joints that are found also in some reptiles. There is a wide blend of stem vertebrae as well as fusion with a chest corset.
Leg
Legs of birds are classified as anisodactyl, zygodactyl, heterodactyl, syndactyl or pamprodactyl. Anisodactyl is the most common arrangement of digits in birds, with three toes forward and one backward. This is common in singers and other birds, and hunting birds such as hawks, eagles, and eagles.
Syndactyly, as happens to birds, such as anisodactyly, except that the third and fourth fingers (the outer and middle toes forward), or the three toes, fuse together, as in the cherry kingfisher Ceryle alcyon I. These are characteristic of Coraciiformes (kingfishers, bee-eaters, rollers, etc.).
Zygodactyly (from Greek ?????, a yoke) is the order of numbers in birds, with two forward-facing toes (numbers two and three) and two returns (digits one and four). This arrangement is most common in arboreal species, especially those that climb trees or climb leaves through foliage. Zygodactyly occurs in parrots, woodpeckers (including flickers), cuckoos (including roadrunners), and some owls. Traces of Zygodactyl have been discovered since 120-110 Ma (early Cretaceous), 50 million years before the first zygodactyl fossils were identified.
Heterodactyly like zygodactyly, except that the numbers three and four point forward and one digit and two point to back. These are found only in trogons, while pamprodactyl is a setting in which all four toes can point forward, or the bird can rotate two toes back to back. This is a characteristic of swift (Apodidae).
Maps Bird anatomy
Muscular system
Most birds have about 175 different muscles, mainly controlling the wings, skin, and legs. The largest muscles in birds are pectoral, or breast muscles, which control the wings and make up about 15 - 25% of the weight of birds being flown. They provide a strong wing stroke essential for flight. The medial muscle to (below) pectoral is supracoracoideus. This raises the wings between the wings. Both muscle groups stick to the keel sternum. This is remarkable, because other vertebrates have muscles to lift the upper limbs that are generally attached to the area behind the spine. Supracoracoideus and pectoral together form about 25-35% of the full weight of the bird.
The skin muscles help the bird in its flight by adjusting its fur, which attaches to the skin muscle and helps the bird in its flight maneuvers.
There are only a few muscles in the stalk and tail, but they are very strong and very important for birds. Pygostyle controls all the movements in the tail and controls the feathers on the tail. This gives the tail a larger surface area that helps keep the birds in the air.
Integumentary system
Scales
Scales of birds consist of keratin, such as beak, claw, and spurs. They are found mainly in the toes and tarsi (lower bird legs), usually up to the tibio-tarsal joint, but can be found further in the legs in some birds. In many eagles and owls, the legs are hairy to (but do not include) their toes. Most bird scales do not overlap significantly, except in the case of kingfishers and woodpeckers. Scales and scales originally thought to be homologous with reptiles; However, recent research has shown that scales in birds evolved after the evolution of feathers.
Bird embryos begin development with delicate skin. In the legs, corneum, or outermost layer, this skin can keratinize, thicken and form the scales. This scale can be set to;
- Cancella - minute scales that are really just thickening and crusting, cross each other with shallow grooves.
- Scutella - scales that are not big enough like scales, like those found on the tail, or the back, of the chicken metatarsus.
- Scutes - the largest scales, usually on the anterior surface of the metatarsus and dorsal surfaces of the toes.
The flute line in anterior metatarsus can be called "acrometatarsium" or "acrotarsium".
The reticula is located on the lateral and medial surface (sides) of the leg and is initially considered to be a separate scale. However, the work of histological and evolutionary developments in this area reveals that this structure lacks beta-keratin (a characteristic of reptile scales) and is composed entirely of alpha-keratin. This, along with their unique structure, has led to the suggestion that this is actually a feather bud being captured early in development.
Rhamphotheca and podotheca
The bills of the crossers have many Herbst blood cells that help them find hidden prey under wet sand, by detecting minute pressure differences in the water. All remaining birds can move the upper part of the upper jaw relative to the brain case. However this is more prevalent in some birds and can be easily detected in parrots.
The area between the eye and the beak on the side of the bird's head is called knowledge. This area is sometimes not hairy, and its skin may be colored, as in many species of cormorant birds.
The scaly covers present at the foot of the bird are called podotheca.
Beak
Beak, bill, or rostrum is the external anatomical structure of birds used for feeding and for treatment, manipulating objects, killing prey, fighting, feeding, dating and feeding children. Although beaks vary in size, shape and color, they share the same basic structure. Two bone projections - the upper and lower mandible - are covered with a thin layer of epidermal keratinization known as rhamphotheca. In most species, two holes known as nares lead to the respiratory system.
Respiratory system
Due to the high metabolic rate required for flight, birds have high oxygen demand. Their highly effective respiratory system helps them meet the demand.
Although birds have lungs, this is a fairly stiff structure, which does not expand and contract as they do in mammals, reptiles and many amphibians. The structure acting as a bellows that ventilates the lungs, is an air sac that is distributed throughout the bird's body. Although the bird's lungs are smaller than mammals of comparable size, the air sacs account for 15% of the total body volume, compared with 7% devoted to alveoli that act as bellows in mammals.
The wall of this air sac does not have a good blood supply so it does not play a direct role in gas exchange. They act like a set of bellows that transfers air indirectly through the parabronchi of a rigid lung.
Birds have no diaphragm, and therefore use their intercostal and abdominal muscles to expand and contract the entire thoracic cavity, thus rhymingly changing the volume of all their airbags simultaneously (illustrated on the right). The active phase of respiration in birds is breathing, requiring respiratory muscle contraction. Relaxation of these muscles causes inhalation.
Three different sets of organs perform respiration - anterior air sacs (interclavicular, cervicals, and anterior thoracics), lungs, and posterior air sacs (tororachic and posterior abdominals). There are usually nine airbags in the system; However, the number can range from seven and twelve, depending on the bird species. Passerines have seven airbags, because the air sacs of the clavicle can be interconnected or fused with anterior piston sacs.
During inhalation, the air environment initially enters the bird through the nostrils from where it is heated, moistened, and filtered in the nasal passages and upper trachea. From there, air enters the lower trachea and continues beyond the syrinx where the tracheal branch points into two primary bronchuses, leading to the two lungs. The primary bronchus enters the lungs to become an intrapulmonary bronchus, which secretes a set of parallel branches called ventrobronchi and, a little further, the equivalent dorsobronchi set. The ends of the air intrusulmonary bronchial discharge into the posterior air sac at the tip of the tail of the bird. Each pair of dorso-ventrobronchi is connected by a large number of parallel microscopic air capillaries (or parabronchi) where gas exchange takes place. As the birds breathe the air the trachea flows through the intrapulmonary bronchus into the posterior air sac, as well as to the dorso bronchus (but not to the ventrobronchi entering the previously strongly believed intrapulmonary bronchus). closed during inhalation. However, recent research has shown that aerodynamic bronchial architecture directs air inhaled away from ventrobronchi openings, into the continuation of the intrapulmonary bronchi into the dorsobronchi and posterior airbags). From dorsobronchi, the air flows through the parabronchi (and therefore the gas exchanger) to the ventrobronchi from which air can only escape into the widespread anterior airbag. Thus, during inhalation, both the posterior and anterior airbags are enlarged, the posterior airbag fills with fresh air being inhaled, while the anterior sacs fill with the "exhaust" (bad oxygen) air just passing through the lungs.
During respiration, the intrapulmonary bronchus is believed to be strictly confined between the area where the ventrobronchi branch dies and the area where the dorsobronchi branch dies. But now it is believed that more complicated aerodynamic features have the same effect. The contracted posterior air sac can only be empty to the dorsobronchi. From there the fresh air from the posterior air bag flows through the parabronchi (in the same direction as it did during the inhalation) to the ventrobronchi. The airways connecting the ventrobronchi and anterior air sac to the intrapulmonary bronchus open during respiration, thus allowing poor air of oxygen from these two organs to escape through the trachea to the outside. Therefore, oxygenated air flows constantly (during the entire cycle of breathing) in one direction through the parabronchi.
The blood flow through the bird's lungs is at right angles to the airflow through the parabronchi, forming a cross-currents flow system (see illustration on the left). The partial pressure of oxygen in the parabronchi decreases along its length when O 2 diffuses into the blood. The blood capillaries that leave the exchanger near the airflow entrance take more O 2 than the capillaries that leave near the outer end of the parabronchi. When the content of all capillaries is mixed, the final partial pressure of oxygen from the pulmonary venous blood of the mixture is higher than in the exhaled air, but still less than half of the air is inhaled, thus reaching approximately the same systemic arterial blood arteries. oxygen pressures like mammals do with their bellow-type lung.
Trachea is a dead space area: the poor oxygen air present at the end of breathing is the first air that enters back into the posterior airbag and lungs. Compared with the mammalian respiratory tract, the volume of dead space in birds is an average of 4.5 times greater than in mammals of the same size. Birds with long necks will have long tracheas, and therefore have to take deeper breaths than mammals to make leeway for their larger dead space volumes. In some birds (eg, whooper swan, Cygnus cygnus), white spoonbill, Platalea leucorodia, bead brood, Grus americana and helmeted curassow, Pauxi pauxi ) the trachea, which some cranes can reach 1.5 m long, rolled back and forth inside the body, drastically improves the ventilation of the dead chamber. The purpose of this amazing feature is unknown.
Air passes indirectly through the lungs during respiration and inspiration, causing, except for the oxygen-poor air space remaining in the trachea after respiration and inhalation at the beginning of inhalation, little or no mixing of new oxygen-rich air with poor air of oxygen ( as happens in the lungs of mammals), just change (from oxygen-rich to poor oxygen) as it moves (direction) through the parabronchi.
The lungs do not have alveoli as mammalian lung does. Instead they contain millions of narrow channels known as parabronchi, connecting the dorsobronchi to the ventrobronchi at both ends of the lung. Air flows anteriorly (caudal to cranial) through parallel parabellchi. The parabronchi has a honeycombed wall. The honeycomb cells are dead air vesicles, called atria , which project radially from parabronchi. The atria is a gas exchange site with simple diffusion. The flow of blood around the parabronchi (and their atria), forms a cross-current gas exchanger (see diagram on the left).
All bird species with the exception of penguins, have small areas of their lungs devoted to "neopulmonic parabronchi". This irregular network of microscopic tubes branches out of the posterior air bag, and opens haphazardly into the dorso- and ventrobronchi, as well as directly into the intrapulmonary bronchus. Unlike the parabronchi, where air moves in the same direction, the air flow in the neopulmonic parabronchi is bidirectional. The neopulmonic parabronchi never reaches more than 25% of the total surface of the gas exchange.
Syrinx is a vocal sound organ that produces bird sounds, located at the base of a bird trachea. Like the mammalian larynx, the sound is generated by the vibrations of air flowing through the organs. Syrinx allows several species of birds to produce highly complex vocalizations, even imitating human speech. In some singers, syrinx can produce more than one vote at a time.
Circulation system
Birds have four heart chambers, the same as mammals, and some reptiles (especially crocodilia). This adaptation allows for efficient transportation of nutrients and oxygen throughout the body, providing birds with energy to fly and maintain high activity levels. The heart of hummingbird ruby ​​is pulsed up to 1,200 times per minute (about 20 beats per second).
Digestive System
Crop
Many birds have muscle bags along the throat called plants. Plants work to soften food and regulate its flow through the system by temporarily storing it. The size and shape of the plant varies considerably among the birds. The Columbidae family members, like pigeons, produce milk of nutritious plants fed to their children with regurgitation.
Proventriculus
The poultry stomach consists of two organs, proventrikulus and rempela that work together during digestion. Proventrikulus is a rod-shaped tube, which is found between the esophagus and the quench, which secretes hydrochloric and pepsinogenic acids into the gastrointestinal tract. The acid converts the inactive pepsinogen into an active proteolytic enzyme, pepsin, which breaks down the specific peptide bonds found in proteins, to produce a set of peptides, which are shorter amino acid chains than the original dietary protein. Gastric juice (hydrochloric acid and pepsinogen) is mixed with the contents of the stomach through muscle contraction of the gizzard.
Gizzard
Gizzard consists of four muscular bands that rotate and destroy food by shifting food from one area to another in the gizzard. Gizzards of several species of herbivorous birds, such as turkeys and quails, contain small pieces of rock or stone called gastroliths that are swallowed by birds to assist in the process of grinding, serving the function of the teeth. The use of gizzard stones is a similarity found between birds and dinosaurs, leaving gastroliths as traces of fossils.
Bowel
The contents of the partially digested and partially digested rhizomes, now called boluses, are passed into the intestine, where pancreatic and intestinal enzymes supplement digestible digestible food. The digestive product is then absorbed through the intestinal mucosa into the blood. The intestines end up through the large intestine in the ventilation or cloaca that serves as a common outlet for kidney and bowel impurities and for egg laying. Unlike mammals, however, many birds do not expend large (grainy) portions of undigested food (eg feathers, feathers, bone fragments, and seed shells) through the cloaca, but vomit it as food pellets.
Drinking behavior
There are three common ways in which birds drink: using gravity itself, sucking, and using the tongue. Fluids are also obtained from food.
Most birds can not be swallowed by the action of "sucking" or "pumping" peristalsis in the esophagus (like humans), and drinking by repeatedly lifting their heads after filling their mouths to allow fluids to flow through gravity, methods typically described as "inhaling" or "tipping up". The notable exception is Columbidae; actually, according to Konrad Lorenz in 1939:
one recognizes the sequence by a single behavioral characteristic, namely that in drinking water is pumped by the esophageal peristaltic that occurs without exception in the sequence. The only other group, showing the same behavior, Pteroclidae, was placed near the dove with only this very old characteristic.
Although this general rule is still valid, since then, observations have been made from some exceptions in both directions.
In addition, special nectar feeders such as sunbirds (Nectariniidae) and hummingbirds (Trochilidae) are drunk using hollowed tongue or tongue-like troughs, and parrots (Psittacidae) drink water.
Many sea birds have glands near the eyes that allow them to drink sea water. Excess salt is removed from the nostrils. Many desert birds get the water they need entirely from their food. Removal of nitrogen waste as uric acid reduces the physiological demand for water, because uric acid is not very toxic and thus does not need to be diluted in as much water.
Reproductive and urogenital systems
Male birds have two testicles that become hundreds of times larger during the mating season to produce sperm. Testes in birds are generally asymmetrical with most birds having larger left testes. Female birds in most families have only one functional ovary (the left), connected to the fallopian tubes - although two ovaries are present in the embryonic stage of each female bird. Some bird species have two functional ovaries, and the Apterygiformes order always retains both ovaries.
Most male birds have no phallus. In male species without phallus, sperm is stored in the seminal glomerum in cloacal jutting before intercourse. During intercourse, women move their tails sideways and men rode females from behind or in front (as in stitchbird), or move very close to it. The cloacae then touches, so the sperm can enter the female reproductive tract. This can happen very quickly, sometimes less than half a second.
Sperm stored in female sperm storage tubules for a period varies from one week to more than 100 days, depending on the species. Then, the eggs will be fertilized individually as they leave the ovaries, before the shell is calcified in the fallopian tubes. After the egg is laid by the female, the embryo continues to expand inside the egg outside the female body.
Many waterfowl and some other birds, such as ostriches and turkeys, have phalluses. This seems to be a primitive condition among birds, most of the birds have lost the phallus. Its length is thought to be related to sperm competition in species that usually mate several times in the breeding season; sperm stored closer to the ovaries are more likely to reach fertilization. Longer and more complex phallies tend to occur in fowls whose females have unusual vaginal anatomical features (such as dead sacs and clockwise coils). This vaginal structure can be used to prevent penetration by the male phallus (the coil counterclockwise). In these species, intercourse is often cruel and women's cooperation is not necessary; women's ability to prevent conception allows women to choose fathers for their children. When not copulating, phallus is hidden inside the proctodeum compartment inside the cloaca, right inside the hole.
After the eggs hatch, parents provide different levels of care in terms of food and protection. Pre-social birds can take care of themselves within minutes of hatching; the altricial weaver is helpless, blind, and naked, and requires extended parental care. Chicks from many birds that nest on land like wild chickens and waders can often run immediately after hatching; Such birds are referred to as nififugous. Even young children with holes, often unable to survive without help. The process by which a girl acquires feathers to fly is called "fledging".
Some birds, such as doves, geese, and red crown cranes, remain with their spouses and can produce offspring regularly.
Kidney
The function of the bird's kidney is similar to that of the more extensive mammalian kidney, but with some important adaptations; while most anatomy remains unchanged in design, several important modifications have occurred during their evolution. A bird has a kidney partner that connects to the lower digestive tract through the ureter. Depending on the bird species, the cortex forms about 71-80% of the kidney mass, while the medulla is much smaller at about 5-15% of the mass. Blood vessels and other tubes form the rest of the mass. Unique to birds is the presence of two types of nephrons (renal functional units) of either a reptile-like nephron located in the cortex and nephrons like mammals located in the medulla. Nephron reptiles are more abundant but do not have the typical loop of Henle seen in mammals. Urine collected by the kidneys is emptied into the cloaca through the ureter and then to the large intestine with peristaltic back.
Nervous system
Birds have acute vision - raptors have eight times sharper vision than humans - thanks to higher photoreceptor density in the retina (up to 1,000,000 per square mm in Buteos , compared with 200,000 for humans ), a large number of neurons in the optic nerve, a second set of eye muscles is not found in other animals, and, in some cases, the overhanging fovea that enlarge the center of the visual field. Many species, including hummingbirds and albatross, have two fovea in each eye. Many birds can detect polarized light.
The ears of birds are adapted to capture the change of tone found in bird song. The common tympanic membrane shape is ovular and slightly conical. Morphological differences in the middle ear are observed among species. Ossicles in green sparrows, blackbirds, song thrushes, and house sparrows are proportionately shorter than those found in birds, Mallard ducks, and seabirds. In bird song, syrinx allows each owner to create complex melodies and tones. The middle avian ear consists of three semicircular canals, each ending up with an ampulla and joining to connect with the macula sacculus and lagena, where the cochlea, the short tube is straight to the outer ear, branched off.
Birds have large mass-to-mass ratio. This is reflected in sophisticated and complex bird intelligence.
Immune system
The immune system of birds resembles other animals. Birds have an innate and adaptive immune system. Birds are susceptible to tumors, immune deficiencies and autoimmune diseases.
Fabrician Exchange
Function
The bursa fabricius, also known as the cloaca bursa, is a lymphoid organ that helps in the production of B lymphocytes during humoral immunity. The bursa fabricius is present during the teenage stage but is curled up, and in sparrow is not seen after the sparrow reaches sexual maturity.
Anatomy
The bursa fabricius is a circular pouch that is connected to the superior dorsal side of the cloaca. The bursa consists of many folds, known as plica, which is coated by more than 10,000 follicles covered by connective tissue and surrounded by mesenchyme. Each follicle consists of the cortex that surrounds the medulla. The home cortex of B lymphocytes is very dense, while the lymphocyte home medullus is loose. The medulla is separated from the lumen by the epithelium and this helps in the transport of epithelial cells to the lumen of the bursa. There are 150,000 B lymphocytes located around each follicle.
See also
- Glossary used in bird topography
References
External links
- Bird skull and skeleton
- Poultry respiratory system
- Histology of the poultry respiratory system
Source of the article : Wikipedia
0 Comments