Ultrastructure (or ultra-structure) is the architecture of cells and biomaterials that is visible at higher magnifications than found on a standard optical light microscope. This traditionally meant the resolution and magnification range of a conventional

transmission electron microscope Transmission electron microscopy (TEM) is a microscopy technique in which a beam of electrons is transmitted through a specimen to form an image. The specimen is most often an ultrathin section less than 100 nm thick or a suspension on a gr ...

(TEM) when viewing biological specimens such as cells, tissue, or organs. Ultrastructure can also be viewed with

scanning electron microscopy A scanning electron microscope (SEM) is a type of electron microscope that produces images of a sample by scanning the surface with a focused beam of electrons. The electrons interact with atoms in the sample, producing various signals that ...

and

super-resolution microscopy Super-resolution microscopy is a series of techniques in optical microscopy that allow such images to have Optical resolution, resolutions higher than those imposed by the Diffraction-limited system, diffraction limit, which is due to the diffra ...

, although TEM is a standard

histology Histology, also known as microscopic anatomy or microanatomy, is the branch of biology that studies the microscopic anatomy of biological tissue (biology), tissues. Histology is the microscopic counterpart to gross anatomy, which looks at large ...

technique for viewing ultrastructure. Such cellular structures as

organelle In cell biology, an organelle is a specialized subunit, usually within a cell (biology), cell, that has a specific function. The name ''organelle'' comes from the idea that these structures are parts of cells, as Organ (anatomy), organs are to th ...

s, which allow the cell to function properly within its specified environment, can be examined at the ultrastructural level. Ultrastructure, along with molecular phylogeny, is a reliable

phylogenetic In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...

way of classifying organisms. Features of ultrastructure are used industrially to control material properties and promote biocompatibility.

History

In 1931, German

engineers Engineers, as practitioners of engineering, are professionals who invent, design, build, maintain and test machines, complex systems, structures, gadgets and materials. They aim to fulfill functional objectives and requirements while consider ...

Max Knoll and Ernst Ruska invented the first electron microscope. With the development and invention of this microscope, the range of observable structures that were able to be explored and analyzed increased immensely, as biologists became progressively interested in the submicroscopic organization of cells. This new area of research concerned itself with substructure, also known as the ultrastructure.

Applications

Many scientists use ultrastructural observations to study the following, including but not limited to: * Human Tumors *

Chloroplast A chloroplast () is a type of membrane-bound organelle, organelle known as a plastid that conducts photosynthesis mostly in plant cell, plant and algae, algal cells. Chloroplasts have a high concentration of chlorophyll pigments which captur ...

s *

Bone A bone is a rigid organ that constitutes part of the skeleton in most vertebrate animals. Bones protect the various other organs of the body, produce red and white blood cells, store minerals, provide structure and support for the body, ...

Platelet Platelets or thrombocytes () are a part of blood whose function (along with the coagulation#Coagulation factors, coagulation factors) is to react to bleeding from blood vessel injury by clumping to form a thrombus, blood clot. Platelets have no ...

s *

Sperm Sperm (: sperm or sperms) is the male reproductive Cell (biology), cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm ...

Biology

A common ultrastructural feature found in

plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...

cells is the formation of calcium oxalate crystals. It has been theorized that these crystals function to store calcium within the cell until it is needed for growth or development. Calcium oxalate crystals can also form in

animal Animals are multicellular, eukaryotic organisms in the Biology, biological Kingdom (biology), kingdom Animalia (). With few exceptions, animals heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, ...

s, and kidney stones are a form of these ultrastructural features. Theoretically,

nanobacteria ''Nanobacterium'' ( , pl. ''nanobacteria'' ) is the unit or member name of a former proposed class of living organisms, specifically cell wall, cell-walled microorganisms, now discredited, with a size much smaller than the generally accepted l ...

could be used to decrease the formation of calcium oxalate kidney stones.

Engineering

Controlling ultrastructure has

engineering Engineering is the practice of using natural science, mathematics, and the engineering design process to Problem solving#Engineering, solve problems within technology, increase efficiency and productivity, and improve Systems engineering, s ...

uses for controlling the behavior of cells. Cells respond readily to changes in their extracellular matrix (ECM), so manufacturing materials to mimic ECM allows for increased control over the cell cycle and

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

expression. Many cells, such as plants, produce calcium oxalate crystals, and these crystals are usually considered ultrastructural components of plant cells. Calcium oxalate is a material that is used to manufacture ceramic glazes and it also has

biomaterial A biomaterial is a substance that has been Biological engineering, engineered to interact with biological systems for a medical purpose – either a therapeutic (treat, augment, repair, or replace a tissue function of the body) or a Medical diag ...

properties. For culturing cells and tissue engineering, this crystal is found in fetal bovine serum, and is an important aspect of the extracellular matrix for culturing cells. Ultrastructure is an important factor to consider when engineering dental implants. Since these devices interface directly with bone, their incorporation to surrounding tissue is necessary to optimal device function. It has been found that applying a load to a healing dental implant allows for increased osseointegration with facial bones. Analyzing the ultrastructure surrounding an implant is useful in determining how biocompatible it is and how the body reacts to it. One study found implanting granules of a biomaterial derived from pig bone caused the human body to incorporate the material into its ultrastructure and form new bone.

Hydroxyapatite Hydroxyapatite (International Mineralogical Association, IMA name: hydroxylapatite) (Hap, HAp, or HA) is a naturally occurring mineral form of calcium apatite with the Chemical formula, formula , often written to denote that the Crystal struc ...

is a biomaterial used to interface medical devices directly to bone by ultrastructure. Grafts can be created along with 𝛃-tricalcium phosphate, and it has been observed that surrounding bone tissue with incorporate the new material into its extracellular matrix. Hydroxyapatite is a highly biocompatible material, and its ultrastructural features, such as crystalline orientation, can be controlled carefully to ensure optimal biocompatibility. Proper crystal fiber orientation can make introduced minerals, like hydroxyapatite, more similar to the biological materials they intend to replace. Controlling ultrastructural features makes obtaining specific material properties possible.

References

External links

*{{Commonscat-inline Electron microscopy Cell anatomy