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Topic

Ultrastructure

About: Ultrastructure is a(n) research topic. Over the lifetime, 5859 publication(s) have been published within this topic receiving 124007 citation(s). The topic is also known as: ultramicroscopic structure.


Papers
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Journal ArticleDOI
TL;DR: The newly discovered epithelial cells contain multiple vesicles that suggest a transport function, possibly for luminal antigenic material or for secretory immunoglobulin, in human intestinal mucosal cell type M cells.
Abstract: The "M" (microfold) cell, a previously unrecognized human intestinal mucosal cell type, is described from studies by light microscopy, transmission electron microscopy, and scanning electron microscopy. M cells, characterized by luminal surface microfolds rather than microvilli, are located in areas of noncolumnar epithelium overlying lymphoid follicles in Peyer's patches. Attenuated M cell processes form a latticework, allowing lymphoid cells to approach to within 0.3 µm of the intestinal lumen while maintaining the integrity of the intestinal epithelium. These newly discovered epithelial cells contain multiple vesicles that suggest a transport function, possibly for luminal antigenic material or for secretory immunoglobulin.

723 citations

Book
01 Jun 1972

614 citations

Journal ArticleDOI
TL;DR: It is concluded from these experiments that the three-dimensional collagen gel can promote dissociation, migration, and acquisition of secretory organelles by differentiated epithelial cells, and can abolish the apical-basal cell polarity characteristic of the original epithelium.
Abstract: This study of epithelial-mesenchymal transformation and epithelial cell polarity in vitro reveals that environmental conditions can have a profound effect on the epithelial phenotype, cell shape, and polarity as expressed by the presence of apical and basal surfaces. A number of different adult and embryonic epithelia were suspended within native collagen gels. Under these conditions, cells elongate, detach from the explants, and migrate as individual cells within the three-dimensional lattice, a previously unknown property of well-differentiated epithelia. Epithelial cells from adult and embryonic anterior lens were studied in detail. Elongated cells derived from the apical surface develop pseudopodia and filopodia characteristic of migratory cells and acquire a morphology and ultrastructure virtually indistinguishable from that of mesenchymal cells in vivo. It is concluded from these experiments that the three-dimensional collagen gel can promote dissociation, migration, and acquisition of secretory organelles by differentiated epithelial cells, and can abolish the apical-basal cell polarity characteristic of the original epithelium.

570 citations

Journal ArticleDOI
TL;DR: In papillary muscles worked in vitro without added substrate, there is a marked depletion of both glycogen and lipid, and no morphological evidence for preferential use of glycogen was found.
Abstract: The ultrastructure of cat papillary muscle was studied with respect to the organization of the contractile material, the structure of the organelles, and the cell junctions. The morphological changes during prolonged work in vitro and some effects of fixation were assessed. The myofilaments are associated in a single coherent bundle extending throughout the fiber cross-section. The absence of discrete "myofibrils" in well preserved cardiac muscle is emphasized. The abundant mitochondria confined in clefts among the myofilaments often have slender prolongations, possibly related to changes in their number or their distribution as energy sources within the contractile mass. The large T tubules that penetrate ventricular cardiac muscle fibers at successive I bands are arranged in rows and are lined with a layer of protein-polysaccharide. Longitudinal connections between T tubules are common. The simple plexiform sarcoplasmic reticulum is continuous across the Z lines, and no circumferential "Z tubules" were identified. Specialized contacts between the reticulum and the sarcolemma are established on the T tubules and the cell periphery via subsarcolemmal saccules or cisterns. At cell junctions, a 20 A gap can be demonstrated between the apposed membranes in those areas commonly interpreted as sites of membrane fusion. In papillary muscles worked in vitro without added substrate, there is a marked depletion of both glycogen and lipid. No morphological evidence for preferential use of glycogen was found.

513 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
20222
202148
202067
201971
201856
201756