From Big Medical Encyclopedia

MICRURGY (grech, mikros small + ergon work, work) — set of methodical receptions and technical means for operations on very small objects (bacteria, protozoa, ova and germs, the isolated cells multicellular), and also for operations on intracellular structures (kernels, chromosomes, mitochondrions). The number of receptions of M. joins microisolation, microdissection (microsection), microinjections, microtransplantation, microcauterization, etc. Mikrooperation, to-rye make under control of small increases in the stereomicroscope on rather large objects (ova of amphibians or erinaceouses, germs and their bodies at different stages of development) unaided micromanipulator (see), it is accepted to carry to microsurgery, and the micromanipulations made by means of special devices and tools under average and big increases in a microscope — to actually micrurgy; the border between these concepts is conditional. Began to refer also thin ophthalmologic and otorhinolaryngological operations made by means of an operative microscope to microsurgery (see. Microsurgery ).

Various microoperations (microisolation, merotomy, i.e. division of a body into parts), it is preferential on protozoa, were made in 19 century Skhauten (S. Schouten, 1903) and Barber (M. by A. Barber, 1904) developed technology of isolation and cultivation of separate bacteria by suction them in the micropipet managed by special exact adaptation. Improvement of these devices led to creation of various micromanipulators, napr, the pneumatic micromanipulator of Fonbryun. There are models of micromanipulators supplied with the television device, the quartz monochromator, an oscilloscope and various electronic devices allowing to make very difficult microoperations, napr, transplantation of kernels, kernels, separate chromosomes, liposomes and other intracellular educations from a cell in a cell.

For performance of micromanipulations use special microtools (microscalpels, tweezers, micropallets, microneedles, micropipets, etc.). Use method of microinjections during the studying of influence of various electrolytes, vital stains and other substances entered directly into cytoplasm during removal or transplantation of various structures, napr, imaginal disks of a drosophila, cellular kernels, etc. The dosage of pressure for giving of the necessary amount of liquid through a micropipet is reached in special devices by rotation of the microscrew, heating of air and other ways.

One of methods M. is introduction of the thinnest microelectrodes in a cell or their leading to its surface. So register bioelectric activity of cells, measure pH and rH (an indicator of redox potential) of cellular structures, make irritation of cells, studying their reactions. Introduction to a cell or leading of microelectrodes to it is carried usually out under control of the cathode oscillograph (see. Microelectrode method of a research ). S. S. Chakhotin (1912) developed a method of local damage of the site of a cell by a bunch of ultraviolet rays to dia. apprx. 4 microns (a method of beam microinjection). Modern optical quantum generators (see. Laser ) give the chance to focus a beam on a smaller square, to 1 micron in dia., and, as the central part of a beam bears big energy, than its periphery, diameter of the site of damage can be narrowed to 0,25 microns [Burns (M. by W. Berns), 1974].

For laser M. installations are created, in to-rykh a microscope it is grouped with various lasers (ruby, argon, neodymium, lasers on dyes); by consecutive changes of primary wavelength of a laser beam it is possible to receive radiation with the wavelength from 260 to 700 nanometers lasting 80 — 200 N/sec. Selection of wavelength of light and energy of a beam, a sensitization of subcellular structures chromophores (acridic orange, cytochrome C, Janus green, a hydrochloride of Chinacrinum), impact on cells Actinomycinum of D create conditions for selective damage of certain cellular organoids. In the best models of such installations the image of a cell is transferred to a video monitor and at the same time registers in the videorecorder. Beam microinjection reaches switching off of separate blastomeres of the developing germ, an inactivation of a kernel, a kernel or separate chromosomes of a cell, damage of sites of chromosomes, mitochondrions, the cellular center, a mitotic spindle, etc. A cellular cover it is possible also prizhech a microthermocauter, than use, naira., in developmental biology for detection of activation centers and differentiation of ova.

Intended for micromanipulations biol, an object is placed in the operational cell where it is immobilized a tweezer or the special microcompressor. Sometimes for fixing of an object in a usual hanging drop it is enough to suck away a micropipet surplus of the environment. Often use special moist chambers with the sidewalls opening for introduction of microtools. Such cameras fill with a liquid paraffin or cultural liquid. If necessary use temperature-controlled cameras, in to-rykh by means of the bimetallic regulator constant temperature is maintained.

Depending on the purposes of microsurgical intervention use various optical devices — from the simple dissection microscope to phase and contrast or darkfield microscope (see).

The m is applied to the solution of many questions of embryology, cytology and genetics. A row physical was defined by M. - chemical characteristics of cellular structures, structure and properties of cellular covers, intercellular connections, mitotic figures and so forth. By means of M. investigate mitochondrions, cilia, flagellums, chromosomes. It is possible to replace from a cell in a cell of a kernel, kernels, virus inclusions, to study products of antibodies single plasmablasts of mammals. By methods M. study various processes of microcirculation, function of various departments of nephron etc.

The special role in a research of functions of a genome and mechanisms of regulation of transcribing and broadcast of genetic information is played by experiences with transplantation of kernels in denucleated ova. So, Gerdon (J, V. of Gurdon, 1977) managed to achieve development of a frog from an ovum, the kernel a cut was replaced with a kernel of a cell of intestines or leather of a tadpole. This experience showed that in the differentiated cells of a kernel can keep a full range of genes of an ovum and synthesize others instead of one RNA and proteins.

In spite of the fact that by means of M. many interesting and important data were obtained, extrapolation of these data on living intact cells demands big discretion and amendments taking into account a measure of physiology of the made microoperations.

Fig. 1. Diagrammatic representation of microtools: 1 — 2 — microneedles (1 — usual, 2 — with limited penetration depth); 3 — 5 — micropipets (3 — for transfer of separate microorganisms, 4 — for intracellular injections, 5 — with a side opening); 6 — 7 — microscalpels (6 — slantwise cut off sterzhenek from glass, 7 — platinum sterzhenek with a splinter from a glass ball); 8 — the micropallet (the cut glass ball); 9 — a microhook; 10 — a microloop; 11 — a microball; 12 — mikroprisos; increase approximately twice.

Microtools in M. are similar on the basic elements to surgical instruments. For different micromanipulations use micropipets, microneedles, microscalpels, micropallets, microloops, microhooks, microelectrodes and some other devices (fig. 1). As material for their production serves in the basic glass of various brands since durability of glass products of the small size does not concede, and often and surpasses durability of metal. Simplicity and speed of production of microtools does them of glass irreplaceable in M. Ispolzuyut the following grades of glass: pyrex, quartz glass, glass of LKB for production of working sites of nek-ry tools, ordinary laboratory tubular glass. Microneedles produce from glass tubes with external to dia. 6 — 7 mm and walls of 2 — 3 mm thick, micropipets — from thin-walled tubes with external to dia. 10 — 15 mm at a thickness of walls of 1 — 1,5 mm. Apply also metals — zinc, cadmium, tin, bismuth, lead and their alloys, and sometimes and other substances, fusible and to be extended under the influence of temperature — shellac, asphalt, selenium, nek-ry polymers, carbohydrates (for soluble needles) etc. As working sites use scales of butterflies and a shchetinokhvostok, armors of diatomic seaweed etc.

Fig. 2. Schematic diagram of the main nodes of a microsmithy: 1 — preparation; 2 — the heater; 3 — the mechanism of fastening and giving of preparation; 4 — the rotary plug of the mechanism of turn of preparation (shooters showed the direction of movement); 5 — a feed mechanism of the heater; 6 — system of air delivery or inert gas; 7 — the mechanism of movement for an extract of pipettes; 8 — the photosensor of the infrared radiation (heating).

Microtools make by means of a gas microburner, but in a crust, time is used more often by special all-purpose instruments — microsmithies. The first such device was developed and created Fonbryun with sotr. (P. Fonbrune, 1932). On the same principles in the USSR more perfect device (fig. 2) was created. Giving to the microtool of the necessary form is carried out by means of micromanipulations by the heater and the preparation in sight of a stereomicroscope. Heaters produce from nichrom or platinum. Temperature of their heating — till 1000 °. Preparation can turn on the rotary plug in the vertical plane. The microsmithy is supplied with system of a gas supply to the zone heating for temperature increase of heating or for tempering of the tool. There is also a device for an extract of micropipets and the detachable device.

The thinnest edges of microneedles can be made by means of the microcauter representing the heater with a platinum tip, to-ry bring in a heated state to the end of a glass microneedle so that they stuck to each other; then extend the necessary edge going further for production of microhooks, microloops etc.

Fig. 3. The diagrammatic representation of the device for microinjections under pressure (in a section): 1 — a micropipet with solution for a microinjection; 2 — the holder of a micropipet; 3 — a tube for giving of pressure; 4 — the drawing-in plug; 5 — a rubber ring (sealant).

Microneedles are distinguished on length and thickness of tips. Microneedles with the dulled ends are a component of a tweezer. Micropipets with a diameter of outlet opening more than 25 microns in combination with a rubber tube and a mouthpiece for a mouth are called mundshtuchny pipettes; for use of pipettes with a diameter less than 25 microns the special devices creating sufficient pressure for moving of liquid to them are required. In micropipets of various designs necessary pressure difference is reached by means of the glass syringe, a mercury column, heating of air in a pipette etc. One of devices for microinjections is shown in fig. 3. Micropipets use also for preparation of microelectrodes.

Store microtools in special boxes or the closed glasswares for protection from breakdown and pollution.

Bibliography: Burns M. V., etc. Laser microirradiation of cells, Quantum electronics, t. 5, No. 10, page 2252, 1978; Of e r d about N of. Regulation of function of genes in development of animals, the lane with English, page 150, M., 1977; To about with t yu to P. G. Microelectrode technics, Kiev, 1960, bibliogr.; Methods of developmental biology, under the editorship of T. A. Detlaf, etc., page 39, 161, M., 1974; Microhandling methods of experimental microbiology, under the editorship of B. A. Fichte, M., 1977, bibliogr.; The guide to cytology, under the editorship of A.S. Troshin, t. 1, page 118, M. — L., 1965; F about N - r yu N of the Item. Methods of micromanipulation, the lane with fr., M., 1951; In e of n s M. W. Biological microirradiation, N. At., 1974; Goldstein L. Nuclear transplantation in ameba, Meth. Cell Physiol., v. 1, p. 97, 1964; Lin T. P. Egg micromanipulation, in book: Meth. in mammalian embryol., ed. by J. C. Daniel, p. 157, San Francisco, 1971.

I. E. Hesin; A. B. Tsypin, Yu. V. Agibalov (tekhn.).