Mesentery: A layer of the peritoneum which attaches the abdominal viscera to the ABDOMINAL WALL and conveys their blood vessels and nerves.Splanchnic Circulation: The circulation of blood through the BLOOD VESSELS supplying the abdominal VISCERA.Venules: The minute vessels that collect blood from the capillary plexuses and join together to form veins.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.Mesenteric Cyst: A rare intra-abdominal tumor in the MESENTERY. Mesenteric cysts are usually benign and can be very large fluid-filled (2000 mL) lesions.Lymphangioma, Cystic: A cystic growth originating from lymphatic tissue. It is usually found in the neck, axilla, or groin.Mesenteric Arteries: Arteries which arise from the abdominal aorta and distribute to most of the intestines.Mesocolon: The fold of peritoneum by which the COLON is attached to the posterior ABDOMINAL WALL.Panniculitis, Peritoneal: INFLAMMATION of the underlying layer of ADIPOSE TISSUE (panniculus) of the PERITONEUM, usually of the MESENTERY or the OMENTUM. There are several forms with various names and are usually characterized by infiltration of LYMPHOCYTES and NEUTROPHILS, fat NECROSIS, and FIBROSIS.Lymphatic System: A system of organs and tissues that process and transport immune cells and LYMPH.Peritoneal Neoplasms: Tumors or cancer of the PERITONEUM.Microcirculation: The circulation of the BLOOD through the MICROVASCULAR NETWORK.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.Peritoneal Diseases: Pathological processes involving the PERITONEUM.Capillaries: The minute vessels that connect the arterioles and venules.Hydroxyethylrutoside: Monohydroxyethyl derivative of rutin. Peripheral circulation stimulant used in treatment of venous disorders.Colon, Sigmoid: A segment of the COLON between the RECTUM and the descending colon.Omentum: A double-layered fold of peritoneum that attaches the STOMACH to other organs in the ABDOMINAL CAVITY.Leukocytes: White blood cells. These include granular leukocytes (BASOPHILS; EOSINOPHILS; and NEUTROPHILS) as well as non-granular leukocytes (LYMPHOCYTES and MONOCYTES).p-Methoxy-N-methylphenethylamine: A potent mast cell degranulator. It is involved in histamine release.Rana temporaria: A species of the family Ranidae occurring in a wide variety of habitats from within the Arctic Circle to South Africa, Australia, etc.Transillumination: Passage of light through body tissues or cavities for examination of internal structures.Methoxamine: An alpha-1 adrenergic agonist that causes prolonged peripheral VASOCONSTRICTION.Colitis, Ischemic: Inflammation of the COLON due to colonic ISCHEMIA resulting from alterations in systemic circulation or local vasculature.Jejunal Neoplasms: Tumors or cancer in the JEJUNUM region of the small intestine (INTESTINE, SMALL).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.Glycocalyx: The carbohydrate-rich zone on the cell surface. This zone can be visualized by a variety of stains as well as by its affinity for lectins. Although most of the carbohydrate is attached to intrinsic plasma membrane molecules, the glycocalyx usually also contains both glycoproteins and proteoglycans that have been secreted into the extracellular space and then adsorbed onto the cell surface. (Alberts et al., Molecular Biology of the Cell, 3d ed, p502)Fibromatosis, Abdominal: A relatively large mass of unusually firm scarlike connective tissue resulting from active participation of fibroblasts, occurring most frequently in the abdominal muscles of women who have borne children. The fibroblasts infiltrate surrounding muscle and fascia. (Stedman, 25th ed)Intestinal Obstruction: Any impairment, arrest, or reversal of the normal flow of INTESTINAL CONTENTS toward the ANAL CANAL.Paraganglia, Chromaffin: Small bodies containing chromaffin cells occurring outside of the adrenal medulla, most commonly near the sympathetic ganglia and in organs such as the kidney, liver, heart and gonads.Arterioles: The smallest divisions of the arteries located between the muscular arteries and the capillaries.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.Intestine, Small: The portion of the GASTROINTESTINAL TRACT between the PYLORUS of the STOMACH and the ILEOCECAL VALVE of the LARGE INTESTINE. It is divisible into three portions: the DUODENUM, the JEJUNUM, and the ILEUM.Sigmoid Neoplasms: Tumors or cancer of the SIGMOID COLON.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.Jejunal Diseases: Pathological development in the JEJUNUM region of the SMALL INTESTINE.Ileal Diseases: Pathological development in the ILEUM including the ILEOCECAL VALVE.Lymphatic Vessels: Tubular vessels that are involved in the transport of LYMPH and LYMPHOCYTES.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.Lymphangioma: A benign tumor resulting from a congenital malformation of the lymphatic system. Lymphangioendothelioma is a type of lymphangioma in which endothelial cells are the dominant component.Endothelium, Lymphatic: Unbroken cellular lining (intima) of the lymph vessels (e.g., the high endothelial lymphatic venules). It is more permeable than vascular endothelium, lacking selective absorption and functioning mainly to remove plasma proteins that have filtered through the capillaries into the tissue spaces.Perfusion: Treatment process involving the injection of fluid into an organ or tissue.Cell Adhesion: Adherence of cells to surfaces or to other cells.Capillary Resistance: The vascular resistance to the flow of BLOOD through the CAPILLARIES portions of the peripheral vascular bed.Intestinal Volvulus: A twisting in the intestine (INTESTINES) that can cause INTESTINAL OBSTRUCTION.Abdominal NeoplasmsCystadenoma, Mucinous: A multilocular tumor with mucin secreting epithelium. They are most often found in the ovary, but are also found in the pancreas, appendix, and rarely, retroperitoneal and in the urinary bladder. They are considered to have low-grade malignant potential.Gonads: The gamete-producing glands, OVARY or TESTIS.Blood Vessels: Any of the tubular vessels conveying the blood (arteries, arterioles, capillaries, venules, and veins).Cell Degranulation: The process of losing secretory granules (SECRETORY VESICLES). This occurs, for example, in mast cells, basophils, neutrophils, eosinophils, and platelets when secretory products are released from the granules by EXOCYTOSIS.Mesenteric Vascular Occlusion: Obstruction of the flow in the SPLANCHNIC CIRCULATION by ATHEROSCLEROSIS; EMBOLISM; THROMBOSIS; STENOSIS; TRAUMA; and compression or intrinsic pressure from adjacent tumors. Rare causes are drugs, intestinal parasites, and vascular immunoinflammatory diseases such as PERIARTERITIS NODOSA and THROMBOANGIITIS OBLITERANS. (From Juergens et al., Peripheral Vascular Diseases, 5th ed, pp295-6)Torsion Abnormality: An abnormal twisting or rotation of a bodily part or member on its axis.Mast Cells: Granulated cells that are found in almost all tissues, most abundantly in the skin and the gastrointestinal tract. Like the BASOPHILS, mast cells contain large amounts of HISTAMINE and HEPARIN. Unlike basophils, mast cells normally remain in the tissues and do not circulate in the blood. Mast cells, derived from the bone marrow stem cells, are regulated by the STEM CELL FACTOR.Microvessels: The finer blood vessels of the vasculature that are generally less than 100 microns in internal diameter.Biological Factors: Endogenously-synthesized compounds that influence biological processes not otherwise classified under ENZYMES; HORMONES or HORMONE ANTAGONISTS.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)Cats: The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801)P-Selectin: Cell adhesion molecule and CD antigen that mediates the adhesion of neutrophils and monocytes to activated platelets and endothelial cells.Rana pipiens: A highly variable species of the family Ranidae in Canada, the United States and Central America. It is the most widely used Anuran in biomedical research.Vasoconstriction: The physiological narrowing of BLOOD VESSELS by contraction of the VASCULAR SMOOTH MUSCLE.Peritoneum: A membrane of squamous EPITHELIAL CELLS, the mesothelial cells, covered by apical MICROVILLI that allow rapid absorption of fluid and particles in the PERITONEAL CAVITY. The peritoneum is divided into parietal and visceral components. The parietal peritoneum covers the inside of the ABDOMINAL WALL. The visceral peritoneum covers the intraperitoneal organs. The double-layered peritoneum forms the MESENTERY that suspends these organs from the abdominal wall.Vasodilation: The physiological widening of BLOOD VESSELS by relaxing the underlying VASCULAR SMOOTH MUSCLE.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.Radiography, Abdominal: Radiographic visualization of the body between the thorax and the pelvis, i.e., within the peritoneal cavity.Digestive System: A group of organs stretching from the MOUTH to the ANUS, serving to breakdown foods, assimilate nutrients, and eliminate waste. In humans, the digestive system includes the GASTROINTESTINAL TRACT and the accessory glands (LIVER; BILIARY TRACT; PANCREAS).Abdomen, Acute: A clinical syndrome with acute abdominal pain that is severe, localized, and rapid in onset. Acute abdomen may be caused by a variety of disorders, injuries, or diseases.Germ Cells: The reproductive cells in multicellular organisms at various stages during GAMETOGENESIS.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.