Biomaterial Database

Ultrastructural differences between rat inner medullary descending and ascending vasa recta;. 1976

M M Schwartz, and M J Karnovsky, and M A Vehkatachalam

The ultrastructure of rat inner medullary vasa recta was studied by both conventional transmission and freeze-fracture electron microscopy. The identify of descending and ascending vasa recta in the inner medulla was established by tracing outer medullary descending vasa recta and ascending vasa recta into the inner medulla, as well as by the incomplete carbon labeling technique to identify isolated descending vessels or loops. As in the outer medulla, descending vessels possess thick continuous endothelium with pinocytotic vesicles budding off the luminal and basal plasma membranes (more numerous in the latter location), but no fenestrae. Ascending vasa show thin, attenuated endothelium with numerous (500 to 800 A fenestrae bridged by 40 A thick fenestral diaphragms. Intercellular junctions in both vessels are zonulae occludens with usually one, and uncommonly two or three zones of outer leaflet membrane fusion. Intramembranous particles are numerous in endothelial plasma membranes of descending vasa recta; similar particles are much fewer in corresponding ascending vasa recta endothelial plasma membranes. The ultrastructural differences between descending vasa recta and ascending vasa recta may reflect markedly different permeability properties, particularly to macromolecules, and may be relevant to recent functional studies on rat inner medullary vasa recta.

UI	MeSH Term	Description	Entries
D007668	Kidney	Body organ that filters blood for the secretion of URINE and that regulates ion concentrations.	Kidneys
D007679	Kidney Medulla	The internal portion of the kidney, consisting of striated conical masses, the renal pyramids, whose bases are adjacent to the cortex and whose apices form prominent papillae projecting into the lumen of the minor calyces.	Kidney Papilla,Kidney Medullas,Kidney Papillas,Medulla, Kidney,Medullas, Kidney,Papilla, Kidney,Papillas, Kidney
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D002448	Cell Adhesion	Adherence of cells to surfaces or to other cells.	Adhesion, Cell,Adhesions, Cell,Cell Adhesions
D002459	Cell Fusion	Fusion of somatic cells in vitro or in vivo, which results in somatic cell hybridization.	Cell Fusions,Fusion, Cell,Fusions, Cell
D004727	Endothelium	A layer of epithelium that lines the heart, blood vessels (ENDOTHELIUM, VASCULAR), lymph vessels (ENDOTHELIUM, LYMPHATIC), and the serous cavities of the body.	Endotheliums
D005260	Female		Females
D005614	Freeze Fracturing	Preparation for electron microscopy of minute replicas of exposed surfaces of the cell which have been ruptured in the frozen state. The specimen is frozen, then cleaved under high vacuum at the same temperature. The exposed surface is shadowed with carbon and platinum and coated with carbon to obtain a carbon replica.	Fracturing, Freeze,Fracturings, Freeze,Freeze Fracturings
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001485	Basement Membrane	A darkly stained mat-like EXTRACELLULAR MATRIX (ECM) that separates cell layers, such as EPITHELIUM from ENDOTHELIUM or a layer of CONNECTIVE TISSUE. The ECM layer that supports an overlying EPITHELIUM or ENDOTHELIUM is called basal lamina. Basement membrane (BM) can be formed by the fusion of either two adjacent basal laminae or a basal lamina with an adjacent reticular lamina of connective tissue. BM, composed mainly of TYPE IV COLLAGEN; glycoprotein LAMININ; and PROTEOGLYCAN, provides barriers as well as channels between interacting cell layers.	Basal Lamina,Basement Lamina,Lamina Densa,Lamina Lucida,Lamina Reticularis,Basement Membranes,Densas, Lamina,Lamina, Basal,Lamina, Basement,Lucida, Lamina,Membrane, Basement,Membranes, Basement,Reticularis, Lamina