Microcirculation: The circulation of the BLOOD through the MICROVASCULAR NETWORK.Arterioles: The smallest divisions of the arteries located between the muscular arteries and the capillaries.Mouth FloorCapillaries: The minute vessels that connect the arterioles and venules.Laser-Doppler Flowmetry: A method of non-invasive, continuous measurement of MICROCIRCULATION. The technique is based on the values of the DOPPLER EFFECT of low-power laser light scattered randomly by static structures and moving tissue particulates.Venules: The minute vessels that collect blood from the capillary plexuses and join together to form veins.Cheek: The part of the face that is below the eye and to the side of the nose and mouth.Microvessels: The finer blood vessels of the vasculature that are generally less than 100 microns in internal diameter.Microscopic Angioscopy: The noninvasive microscopic examination of the microcirculation, commonly done in the nailbed or conjunctiva. In addition to the capillaries themselves, observations can be made of passing blood cells or intravenously injected substances. This is not the same as endoscopic examination of blood vessels (ANGIOSCOPY).Microscopy, Video: Microscopy in which television cameras are used to brighten magnified images that are otherwise too dark to be seen with the naked eye. It is used frequently in TELEPATHOLOGY.Leukocytes: White blood cells. These include granular leukocytes (BASOPHILS; EOSINOPHILS; and NEUTROPHILS) as well as non-granular leukocytes (LYMPHOCYTES and MONOCYTES).Blood Flow Velocity: A value equal to the total volume flow divided by the cross-sectional area of the vascular bed.Liver Circulation: The circulation of BLOOD through the LIVER.Regional Blood Flow: The flow of BLOOD through or around an organ or region of the body.Vasodilation: The physiological widening of BLOOD VESSELS by relaxing the underlying VASCULAR SMOOTH MUSCLE.Splanchnic Circulation: The circulation of blood through the BLOOD VESSELS supplying the abdominal VISCERA.Coronary Circulation: The circulation of blood through the CORONARY VESSELS of the HEART.Acridine Orange: A cationic cytochemical stain specific for cell nuclei, especially DNA. It is used as a supravital stain and in fluorescence cytochemistry. It may cause mutations in microorganisms.Retinal Vessels: The blood vessels which supply and drain the RETINA.Endothelium, Vascular: Single pavement layer of cells which line the luminal surface of the entire vascular system and regulate the transport of macromolecules and blood components.Skin: The outer covering of the body that protects it from the environment. It is composed of the DERMIS and the EPIDERMIS.Vasodilator Agents: Drugs used to cause dilation of the blood vessels.Mesocricetus: A genus of the family Muridae having three species. The present domesticated strains were developed from individuals brought from Syria. They are widely used in biomedical research.Leukocyte Rolling: Movement of tethered, spherical LEUKOCYTES along the endothelial surface of the microvasculature. The tethering and rolling involves interaction with SELECTINS and other adhesion molecules in both the ENDOTHELIUM and leukocyte. The rolling leukocyte then becomes activated by CHEMOKINES, flattens out, and firmly adheres to the endothelial surface in preparation for transmigration through the interendothelial cell junction. (From Abbas, Cellular and Molecular Immunology, 3rd ed)Pia Mater: The innermost layer of the three meninges covering the brain and spinal cord. It is the fine vascular membrane that lies under the ARACHNOID and the DURA MATER.Vasoconstriction: The physiological narrowing of BLOOD VESSELS by contraction of the VASCULAR SMOOTH MUSCLE.Fluorescein-5-isothiocyanate: Fluorescent probe capable of being conjugated to tissue and proteins. It is used as a label in fluorescent antibody staining procedures as well as protein- and amino acid-binding techniques.Capillary Permeability: The property of blood capillary ENDOTHELIUM that allows for the selective exchange of substances between the blood and surrounding tissues and through membranous barriers such as the BLOOD-AIR BARRIER; BLOOD-AQUEOUS BARRIER; BLOOD-BRAIN BARRIER; BLOOD-NERVE BARRIER; BLOOD-RETINAL BARRIER; and BLOOD-TESTIS BARRIER. Small lipid-soluble molecules such as carbon dioxide and oxygen move freely by diffusion. Water and water-soluble molecules cannot pass through the endothelial walls and are dependent on microscopic pores. These pores show narrow areas (TIGHT JUNCTIONS) which may limit large molecule movement.Hemodynamics: The movement and the forces involved in the movement of the blood through the CARDIOVASCULAR SYSTEM.Cerebrovascular Circulation: The circulation of blood through the BLOOD VESSELS of the BRAIN.Hemorheology: The deformation and flow behavior of BLOOD and its elements i.e., PLASMA; ERYTHROCYTES; WHITE BLOOD CELLS; and BLOOD PLATELETS.Mesentery: A layer of the peritoneum which attaches the abdominal viscera to the ABDOMINAL WALL and conveys their blood vessels and nerves.Nails: The thin, horny plates that cover the dorsal surfaces of the distal phalanges of the fingers and toes of primates.Corrosion Casting: A tissue preparation technique that involves the injecting of plastic (acrylates) into blood vessels or other hollow viscera and treating the tissue with a caustic substance. This results in a negative copy or a solid replica of the enclosed space of the tissue that is ready for viewing under a scanning electron microscope.Reperfusion Injury: Adverse functional, metabolic, or structural changes in ischemic tissues resulting from the restoration of blood flow to the tissue (REPERFUSION), including swelling; HEMORRHAGE; NECROSIS; and damage from FREE RADICALS. The most common instance is MYOCARDIAL REPERFUSION INJURY.Diagnostic Techniques, Cardiovascular: Methods and procedures for the diagnosis of diseases or dysfunction of the cardiovascular system or its organs or demonstration of their physiological processes.Renal Circulation: The circulation of the BLOOD through the vessels of the KIDNEY.Skin Window Technique: A technique to study CELL MIGRATION in the INFLAMMATION process or during immune reactions. After an area on the skin is abraded, the movement of cells in the area is followed via microscopic observation of the exudate through a coverslip or tissue culture chamber placed over the area.Nitric Oxide: A free radical gas produced endogenously by a variety of mammalian cells, synthesized from ARGININE by NITRIC OXIDE SYNTHASE. Nitric oxide is one of the ENDOTHELIUM-DEPENDENT RELAXING FACTORS released by the vascular endothelium and mediates VASODILATION. It also inhibits platelet aggregation, induces disaggregation of aggregated platelets, and inhibits platelet adhesion to the vascular endothelium. Nitric oxide activates cytosolic GUANYLATE CYCLASE and thus elevates intracellular levels of CYCLIC GMP.Fluorophotometry: Measurement of light given off by fluorescein in order to assess the integrity of various ocular barriers. The method is used to investigate the blood-aqueous barrier, blood-retinal barrier, aqueous flow measurements, corneal endothelial permeability, and tear flow dynamics.Cell Adhesion: Adherence of cells to surfaces or to other cells.Vascular Resistance: The force that opposes the flow of BLOOD through a vascular bed. It is equal to the difference in BLOOD PRESSURE across the vascular bed divided by the CARDIAC OUTPUT.Rats, Wistar: A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.Blood Pressure: PRESSURE of the BLOOD on the ARTERIES and other BLOOD VESSELS.Nitroprusside: A powerful vasodilator used in emergencies to lower blood pressure or to improve cardiac function. It is also an indicator for free sulfhydryl groups in proteins.Hyperemia: The presence of an increased amount of blood in a body part or an organ leading to congestion or engorgement of blood vessels. Hyperemia can be due to increase of blood flow into the area (active or arterial), or due to obstruction of outflow of blood from the area (passive or venous).Iontophoresis: Therapeutic introduction of ions of soluble salts into tissues by means of electric current. In medical literature it is commonly used to indicate the process of increasing the penetration of drugs into surface tissues by the application of electric current. It has nothing to do with ION EXCHANGE; AIR IONIZATION nor PHONOPHORESIS, none of which requires current.Oxygen: An element with atomic symbol O, atomic number 8, and atomic weight [15.99903; 15.99977]. It is the most abundant element on earth and essential for respiration.Vasomotor System: The neural systems which act on VASCULAR SMOOTH MUSCLE to control blood vessel diameter. The major neural control is through the sympathetic nervous system.Erythrocytes: Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.Blood Viscosity: The internal resistance of the BLOOD to shear forces. The in vitro measure of whole blood viscosity is of limited clinical utility because it bears little relationship to the actual viscosity within the circulation, but an increase in the viscosity of circulating blood can contribute to morbidity in patients suffering from disorders such as SICKLE CELL ANEMIA and POLYCYTHEMIA.Microscopy: The use of instrumentation and techniques for visualizing material and details that cannot be seen by the unaided eye. It is usually done by enlarging images, transmitted by light or electron beams, with optical or magnetic lenses that magnify the entire image field. With scanning microscopy, images are generated by collecting output from the specimen in a point-by-point fashion, on a magnified scale, as it is scanned by a narrow beam of light or electrons, a laser, a conductive probe, or a topographical probe.Rheology: The study of the deformation and flow of matter, usually liquids or fluids, and of the plastic flow of solids. The concept covers consistency, dilatancy, liquefaction, resistance to flow, shearing, thixotrophy, and VISCOSITY.Models, Cardiovascular: Theoretical representations that simulate the behavior or activity of the cardiovascular system, processes, or phenomena; includes the use of mathematical equations, computers and other electronic equipment.Rats, Sprague-Dawley: A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.Dextrans: A group of glucose polymers made by certain bacteria. Dextrans are used therapeutically as plasma volume expanders and anticoagulants. They are also commonly used in biological experimentation and in industry for a wide variety of purposes.Microscopy, Fluorescence: Microscopy of specimens stained with fluorescent dye (usually fluorescein isothiocyanate) or of naturally fluorescent materials, which emit light when exposed to ultraviolet or blue light. Immunofluorescence microscopy utilizes antibodies that are labeled with fluorescent dye.Vasoconstrictor Agents: Drugs used to cause constriction of the blood vessels.Acetylcholine: A neurotransmitter found at neuromuscular junctions, autonomic ganglia, parasympathetic effector junctions, a subset of sympathetic effector junctions, and at many sites in the central nervous system.Hydroxyethyl Starch Derivatives: Starches that have been chemically modified so that a percentage of OH groups are substituted with 2-hydroxyethyl ether groups.Endotoxemia: A condition characterized by the presence of ENDOTOXINS in the blood. On lysis, the outer cell wall of gram-negative bacteria enters the systemic circulation and initiates a pathophysiologic cascade of pro-inflammatory mediators.Coronary Vessels: The veins and arteries of the HEART.P-Selectin: Cell adhesion molecule and CD antigen that mediates the adhesion of neutrophils and monocytes to activated platelets and endothelial cells.Ischemia: A hypoperfusion of the BLOOD through an organ or tissue caused by a PATHOLOGIC CONSTRICTION or obstruction of its BLOOD VESSELS, or an absence of BLOOD CIRCULATION.Hematocrit: The volume of packed RED BLOOD CELLS in a blood specimen. The volume is measured by centrifugation in a tube with graduated markings, or with automated blood cell counters. It is an indicator of erythrocyte status in disease. For example, ANEMIA shows a low value; POLYCYTHEMIA, a high value.Microscopy, Polarization: Microscopy using polarized light in which phenomena due to the preferential orientation of optical properties with respect to the vibration plane of the polarized light are made visible and correlated parameters are made measurable.Erythrocyte Deformability: Ability of ERYTHROCYTES to change shape as they pass through narrow spaces, such as the microvasculature.Blood Gas Monitoring, Transcutaneous: The noninvasive measurement or determination of the partial pressure (tension) of oxygen and/or carbon dioxide locally in the capillaries of a tissue by the application to the skin of a special set of electrodes. These electrodes contain photoelectric sensors capable of picking up the specific wavelengths of radiation emitted by oxygenated versus reduced hemoglobin.Disease Models, Animal: Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Video Recording: The storing or preserving of video signals for television to be played back later via a transmitter or receiver. Recordings may be made on magnetic tape or discs (VIDEODISC RECORDING).Pancreatitis: INFLAMMATION of the PANCREAS. Pancreatitis is classified as acute unless there are computed tomographic or endoscopic retrograde cholangiopancreatographic findings of CHRONIC PANCREATITIS (International Symposium on Acute Pancreatitis, Atlanta, 1992). The two most common forms of acute pancreatitis are ALCOHOLIC PANCREATITIS and gallstone pancreatitis.Muscle, Skeletal: A subtype of striated muscle, attached by TENDONS to the SKELETON. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles.Tongue DiseasesForearm: Part of the arm in humans and primates extending from the ELBOW to the WRIST.Adenosine: A nucleoside that is composed of ADENINE and D-RIBOSE. Adenosine or adenosine derivatives play many important biological roles in addition to being components of DNA and RNA. Adenosine itself is a neurotransmitter.Bradykinin: A nonapeptide messenger that is enzymatically produced from KALLIDIN in the blood where it is a potent but short-lived agent of arteriolar dilation and increased capillary permeability. Bradykinin is also released from MAST CELLS during asthma attacks, from gut walls as a gastrointestinal vasodilator, from damaged tissues as a pain signal, and may be a neurotransmitter.Hemodilution: Reduction of blood viscosity usually by the addition of cell free solutions. Used clinically (1) in states of impaired microcirculation, (2) for replacement of intraoperative blood loss without homologous blood transfusion, and (3) in cardiopulmonary bypass and hypothermia.Cricetinae: A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.Perfusion: Treatment process involving the injection of fluid into an organ or tissue.Mesenteric Veins: Veins which return blood from the intestines; the inferior mesenteric vein empties into the splenic vein, the superior mesenteric vein joins the splenic vein to form the portal vein.Pancreas: A nodular organ in the ABDOMEN that contains a mixture of ENDOCRINE GLANDS and EXOCRINE GLANDS. The small endocrine portion consists of the ISLETS OF LANGERHANS secreting a number of hormones into the blood stream. The large exocrine portion (EXOCRINE PANCREAS) is a compound acinar gland that secretes several digestive enzymes into the pancreatic ductal system that empties into the DUODENUM.Resuscitation: The restoration to life or consciousness of one apparently dead. (Dorland, 27th ed)Capillary Leak Syndrome: A condition characterized by recurring episodes of fluid leaking from capillaries into extra-vascular compartments causing hematocrit to rise precipitously. If not treated, generalized vascular leak can lead to generalized EDEMA; SHOCK; cardiovascular collapse; and MULTIPLE ORGAN FAILURE.Ophthalmoscopes: Devices for examining the interior of the eye, permitting the clear visualization of the structures of the eye at any depth. (UMDNS, 1999)Microspheres: Small uniformly-sized spherical particles, of micrometer dimensions, frequently labeled with radioisotopes or various reagents acting as tags or markers.Contrast Media: Substances used to allow enhanced visualization of tissues.Pulmonary Circulation: The circulation of the BLOOD through the LUNGS.Nitroarginine: An inhibitor of nitric oxide synthetase which has been shown to prevent glutamate toxicity. Nitroarginine has been experimentally tested for its ability to prevent ammonia toxicity and ammonia-induced alterations in brain energy and ammonia metabolites. (Neurochem Res 1995:200(4):451-6)Vivisection: The cutting of or surgical operation on a living animal, usually for physiological or pathological investigation. (from Merriam-Webster's Collegiate Dict, 10th ed)Transillumination: Passage of light through body tissues or cavities for examination of internal structures.Ear: The hearing and equilibrium system of the body. It consists of three parts: the EXTERNAL EAR, the MIDDLE EAR, and the INNER EAR. Sound waves are transmitted through this organ where vibration is transduced to nerve signals that pass through the ACOUSTIC NERVE to the CENTRAL NERVOUS SYSTEM. The inner ear also contains the vestibular organ that maintains equilibrium by transducing signals to the VESTIBULAR NERVE.Sepsis: Systemic inflammatory response syndrome with a proven or suspected infectious etiology. When sepsis is associated with organ dysfunction distant from the site of infection, it is called severe sepsis. When sepsis is accompanied by HYPOTENSION despite adequate fluid infusion, it is called SEPTIC SHOCK.Oxygen Consumption: The rate at which oxygen is used by a tissue; microliters of oxygen STPD used per milligram of tissue per hour; the rate at which oxygen enters the blood from alveolar gas, equal in the steady state to the consumption of oxygen by tissue metabolism throughout the body. (Stedman, 25th ed, p346)Biological Factors: Endogenously-synthesized compounds that influence biological processes not otherwise classified under ENZYMES; HORMONES or HORMONE ANTAGONISTS.Image Processing, Computer-Assisted: A technique of inputting two-dimensional images into a computer and then enhancing or analyzing the imagery into a form that is more useful to the human observer.Shock, Septic: Sepsis associated with HYPOTENSION or hypoperfusion despite adequate fluid resuscitation. Perfusion abnormalities may include, but are not limited to LACTIC ACIDOSIS; OLIGURIA; or acute alteration in mental status.Blood Circulation: The movement of the BLOOD as it is pumped through the CARDIOVASCULAR SYSTEM.Arteries: The vessels carrying blood away from the heart.Optical Processes: Behavior of LIGHT and its interactions with itself and materials.Ceruletide: A specific decapeptide obtained from the skin of Hila caerulea, an Australian amphibian. Caerulein is similar in action and composition to CHOLECYSTOKININ. It stimulates gastric, biliary, and pancreatic secretion; and certain smooth muscle. It is used in paralytic ileus and as diagnostic aid in pancreatic malfunction.Mice, Inbred C57BLEndothelial Cells: Highly specialized EPITHELIAL CELLS that line the HEART; BLOOD VESSELS; and lymph vessels, forming the ENDOTHELIUM. They are polygonal in shape and joined together by TIGHT JUNCTIONS. The tight junctions allow for variable permeability to specific macromolecules that are transported across the endothelial layer.Papaverine: An alkaloid found in opium but not closely related to the other opium alkaloids in its structure or pharmacological actions. It is a direct-acting smooth muscle relaxant used in the treatment of impotence and as a vasodilator, especially for cerebral vasodilation. The mechanism of its pharmacological actions is not clear, but it apparently can inhibit phosphodiesterases and it may have direct actions on calcium channels.Plasma Substitutes: Any liquid used to replace blood plasma, usually a saline solution, often with serum albumins, dextrans or other preparations. These substances do not enhance the oxygen- carrying capacity of blood, but merely replace the volume. They are also used to treat dehydration.Swine: Any of various animals that constitute the family Suidae and comprise stout-bodied, short-legged omnivorous mammals with thick skin, usually covered with coarse bristles, a rather long mobile snout, and small tail. Included are the genera Babyrousa, Phacochoerus (wart hogs), and Sus, the latter containing the domestic pig (see SUS SCROFA).Nitric Oxide Synthase: An NADPH-dependent enzyme that catalyzes the conversion of L-ARGININE and OXYGEN to produce CITRULLINE and NITRIC OXIDE.Models, Animal: Non-human animals, selected because of specific characteristics, for use in experimental research, teaching, or testing.Blood Vessels: Any of the tubular vessels conveying the blood (arteries, arterioles, capillaries, venules, and veins).Liver: A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.Blood Substitutes: Substances that are used in place of blood, for example, as an alternative to BLOOD TRANSFUSIONS after blood loss to restore BLOOD VOLUME and oxygen-carrying capacity to the blood circulation, or to perfuse isolated organs.Ophthalmoscopy: Examination of the interior of the eye with an ophthalmoscope.Erythrocyte Aggregation: The formation of clumps of RED BLOOD CELLS under low or non-flow conditions, resulting from the attraction forces between the red blood cells. The cells adhere to each other in rouleaux aggregates. Slight mechanical force, such as occurs in the circulation, is enough to disperse these aggregates. Stronger or weaker than normal aggregation may result from a variety of effects in the ERYTHROCYTE MEMBRANE or in BLOOD PLASMA. The degree of aggregation is affected by ERYTHROCYTE DEFORMABILITY, erythrocyte membrane sialylation, masking of negative surface charge by plasma proteins, etc. BLOOD VISCOSITY and the ERYTHROCYTE SEDIMENTATION RATE are affected by the amount of erythrocyte aggregation and are parameters used to measure the aggregation.Edema: Abnormal fluid accumulation in TISSUES or body cavities. Most cases of edema are present under the SKIN in SUBCUTANEOUS TISSUE.Diagnostic Imaging: Any visual display of structural or functional patterns of organs or tissues for diagnostic evaluation. It includes measuring physiologic and metabolic responses to physical and chemical stimuli, as well as ultramicroscopy.Enzyme Inhibitors: Compounds or agents that combine with an enzyme in such a manner as to prevent the normal substrate-enzyme combination and the catalytic reaction.Organ Preservation: The process by which organs are kept viable outside of the organism from which they were removed (i.e., kept from decay by means of a chemical agent, cooling, or a fluid substitute that mimics the natural state within the organism).Hydronephrosis: Abnormal enlargement or swelling of a KIDNEY due to dilation of the KIDNEY CALICES and the KIDNEY PELVIS. It is often associated with obstruction of the URETER or chronic kidney diseases that prevents normal drainage of urine into the URINARY BLADDER.Fluorescein Angiography: Visualization of a vascular system after intravenous injection of a fluorescein solution. The images may be photographed or televised. It is used especially in studying the retinal and uveal vasculature.Reperfusion: Restoration of blood supply to tissue which is ischemic due to decrease in normal blood supply. The decrease may result from any source including atherosclerotic obstruction, narrowing of the artery, or surgical clamping. It is primarily a procedure for treating infarction or other ischemia, by enabling viable ischemic tissue to recover, thus limiting further necrosis. However, it is thought that reperfusion can itself further damage the ischemic tissue, causing REPERFUSION INJURY.Lasers: An optical source that emits photons in a coherent beam. Light Amplification by Stimulated Emission of Radiation (LASER) is brought about using devices that transform light of varying frequencies into a single intense, nearly nondivergent beam of monochromatic radiation. Lasers operate in the infrared, visible, ultraviolet, or X-ray regions of the spectrum.Histamine: An amine derived by enzymatic decarboxylation of HISTIDINE. It is a powerful stimulant of gastric secretion, a constrictor of bronchial smooth muscle, a vasodilator, and also a centrally acting neurotransmitter.Inflammation: A pathological process characterized by injury or destruction of tissues caused by a variety of cytologic and chemical reactions. It is usually manifested by typical signs of pain, heat, redness, swelling, and loss of function.Skin Temperature: The TEMPERATURE at the outer surface of the body.Erythrocytes, Abnormal: Oxygen-carrying RED BLOOD CELLS in mammalian blood that are abnormal in structure or function.omega-N-Methylarginine: A competitive inhibitor of nitric oxide synthetase.Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Partial Pressure: The pressure that would be exerted by one component of a mixture of gases if it were present alone in a container. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Blood Volume: Volume of circulating BLOOD. It is the sum of the PLASMA VOLUME and ERYTHROCYTE VOLUME.Leukocyte Count: The number of WHITE BLOOD CELLS per unit volume in venous BLOOD. A differential leukocyte count measures the relative numbers of the different types of white cells.Endothelin-1: A 21-amino acid peptide produced in a variety of tissues including endothelial and vascular smooth-muscle cells, neurons and astrocytes in the central nervous system, and endometrial cells. It acts as a modulator of vasomotor tone, cell proliferation, and hormone production. (N Eng J Med 1995;333(6):356-63)NG-Nitroarginine Methyl Ester: A non-selective inhibitor of nitric oxide synthase. It has been used experimentally to induce hypertension.Colloids: Two-phase systems in which one is uniformly dispersed in another as particles small enough so they cannot be filtered or will not settle out. The dispersing or continuous phase or medium envelops the particles of the discontinuous phase. All three states of matter can form colloids among each other.Acepromazine: A phenothiazine that is used in the treatment of PSYCHOSES.Acute Disease: Disease having a short and relatively severe course.Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Blood-Brain Barrier: Specialized non-fenestrated tightly-joined ENDOTHELIAL CELLS with TIGHT JUNCTIONS that form a transport barrier for certain substances between the cerebral capillaries and the BRAIN tissue.Mouth Mucosa: Lining of the ORAL CAVITY, including mucosa on the GUMS; the PALATE; the LIP; the CHEEK; floor of the mouth; and other structures. The mucosa is generally a nonkeratinized stratified squamous EPITHELIUM covering muscle, bone, or glands but can show varying degree of keratinization at specific locations.Gastric Mucosa: Lining of the STOMACH, consisting of an inner EPITHELIUM, a middle LAMINA PROPRIA, and an outer MUSCULARIS MUCOSAE. The surface cells produce MUCUS that protects the stomach from attack by digestive acid and enzymes. When the epithelium invaginates into the LAMINA PROPRIA at various region of the stomach (CARDIA; GASTRIC FUNDUS; and PYLORUS), different tubular gastric glands are formed. These glands consist of cells that secrete mucus, enzymes, HYDROCHLORIC ACID, or hormones.Capillary Resistance: The vascular resistance to the flow of BLOOD through the CAPILLARIES portions of the peripheral vascular bed.Perfusion Imaging: The creation and display of functional images showing where the blood flow reaches by following the distribution of tracers injected into the blood stream.Hemoglobins: The oxygen-carrying proteins of ERYTHROCYTES. They are found in all vertebrates and some invertebrates. The number of globin subunits in the hemoglobin quaternary structure differs between species. Structures range from monomeric to a variety of multimeric arrangements.Albumins: Water-soluble proteins found in egg whites, blood, lymph, and other tissues and fluids. They coagulate upon heating.Annexin A1: Protein of the annexin family exhibiting lipid interaction and steroid-inducibility.Microtechnology: Manufacturing technology for making microscopic devices in the micrometer range (typically 1-100 micrometers), such as integrated circuits or MEMS. The process usually involves replication and parallel fabrication of hundreds or millions of identical structures using various thin film deposition techniques and carried out in environmentally-controlled clean rooms.Varicose Ulcer: Skin breakdown or ulceration caused by VARICOSE VEINS in which there is too much hydrostatic pressure in the superficial venous system of the leg. Venous hypertension leads to increased pressure in the capillary bed, transudation of fluid and proteins into the interstitial space, altering blood flow and supply of nutrients to the skin and subcutaneous tissues, and eventual ulceration.Shock, Hemorrhagic: Acute hemorrhage or excessive fluid loss resulting in HYPOVOLEMIA.Cerebral Veins: Veins draining the cerebrum.Muscle Tonus: The state of activity or tension of a muscle beyond that related to its physical properties, that is, its active resistance to stretch. In skeletal muscle, tonus is dependent upon efferent innervation. (Stedman, 25th ed)Brain: The part of CENTRAL NERVOUS SYSTEM that is contained within the skull (CRANIUM). Arising from the NEURAL TUBE, the embryonic brain is comprised of three major parts including PROSENCEPHALON (the forebrain); MESENCEPHALON (the midbrain); and RHOMBENCEPHALON (the hindbrain). The developed brain consists of CEREBRUM; CEREBELLUM; and other structures in the BRAIN STEM.