Counting dendritic spines in brain tissue slices by image correlation spectroscopy analysis

Growth of new micrometre sized projections called dendritic spines in neurones has been linked to the encoding of long‐term memories in vertebrates. Numerous studies have been carried out at both the light and electron microscopy level to quantify dendritic spine densities in brain tissue in laboratory animals. Currently, such efforts using light microscopy have relied on manual counting of spines in confocal or two‐photon optical slice images of tissue containing fluorescently labelled spines. This manual approach can be slow and tedious, especially for samples with high spine densities. We introduce an alternative way of performing spine counting that uses an applied image intensity threshold followed by spatial image correlation spectroscopy (ICS) analysis. We investigated the effect of particle sizes above the diffraction limit on the autocorrelation analysis as well as the influence of background fluorescence. Our results show that, for well labelled cerebellar tissue samples imaged with a signal‐to‐noise ratio of 5 or greater, ICS‐based spine counts can be conducted with the same 15–20% precision as manual counting, but much more rapidly.     

3D reconstruction of high-resolution STED microscope images

Tackling biological problems often involves the imaging and localization of cellular structures on the nanometer scale. Although optical super-resolution below 100 nm can be readily attained with stimulated emission depletion (STED) and photoswitching microscopy methods, attaining an axial resolution <100 nm with focused light generally required the use of two lenses in a 4Pi configuration or exceptionally bright photochromic fluorophores. Here, we describe a simple technical solution for 3D nanoscopy of fixed samples: biological specimens are fluorescently labeled, embedded in a polymer resin, cut into thin sections, and then imaged via STED microscopy with nanoscale resolution. This approach allows a 3D image reconstruction with a resolution <80 nm in all directions using available state-of-the art STED microscopes.     

A protocol for registration and correction of multicolour STED superresolution images

Multicolour fluorescence imaging by STimulated Emission Depletion (STED) superresolution microscopy with doughnut‐shaped STED laser beams based on different wavelengths for each colour channel requires precise image registration. This is especially important when STED imaging is used for co‐localisation studies of two or more native proteins in biological specimens to analyse nanometric subcellular spatial arrangements. We developed a robust postprocessing image registration protocol, with the aim to verify and ultimately optimise multicolour STED image quality. Importantly, this protocol will support any subsequent quantitative localisation analysis at nanometric scales. Henceforth, using an approach that registers each colour channel present during STED imaging individually, this protocol reliably corrects for optical aberrations and inadvertent sample drift. To achieve the latter goal, the protocol combines the experimental sample information, from corresponding STED and confocal images using the same optical beam path and setup, with that of an independent calibration sample. As a result, image registration is based on a strategy that maximises the cross‐correlation between sequentially acquired images of the experimental sample, which are strategically combined by the protocol. We demonstrate the general applicability of the image registration protocol by co‐staining of the ryanodine receptor calcium release channel in primary mouse cardiomyocytes. To validate this new approach, we identify user‐friendly criteria, which – if fulfilled – support optimal image registration. In summary, we introduce a new method for image registration and rationally based postprocessing steps through a highly standardised protocol for multicolour STED imaging, which directly supports the reproducibility of protein co‐localisation analyses. Although the reference protocol is discussed exemplarily for two‐colour STED imaging, it can be readily expanded to three or more colours and STED channels.     

Morphological change tracking of dendritic spines based on structural features

Identification and tracking of dendritic spine morphology from two-dimensional time-lapsed images plays an important role in neurobiological research. Such analysis can enable us to derive a correlation between morphological characteristics and molecular mechanism of dendritic spine development and remodelling. Moreover, Neuronal morphology of hippocampal Cornu Ammonis 1 region is critical for understanding the Alzheimer's disease. Therefore, we need to extract and trace the dendritic spines accurately for examining their development and remodelling processes, which are related to functions of hippocampal Cornu Ammonis 1. There are some problems to be solved in related researches. Noise due to the properties of optical microscopes makes it difficult to identify and trace dendritic spines accurately. To solve these problems, in this paper we present a local spine detection technique minimizing noise influence in two-dimensional optical microscopy images. Also, we suggest an efficient mapping method for tracking the dynamics of dendritic spines to measure their morphological changes quantitatively. First, to utilize structural feature of spines, which are small protrusions of tree-like dendrites, we extract the tips of each dendritic branch and use this position as an initial contour position for a deformable model-based segmentation. We then use a geodesic active contour model to detect the spines accurately. Secondly, we apply an optical flow method, which takes into account both structure and movement of objects, to map every time-series image frame. Proposed method provides accurate measurements of dendritic spine length, volume, shape classification for time-lapse images of dendrites of hippocampal neurons. We compared the proposed spine detection algorithm with manual method performed by biologists and noncommercial software NeuronIQ. In particular, this method is able to segment dendritic spines better than existing methods with high sensitivity in adjacent spines and noisy images. Also the algorithm performs well compared to a human analyser.     

Porcine Choroid plexus epithelial cells in culture: regulation of barrier properties and transport processes

The epithelial cells of the choroid plexus are the structural basis of the blood-cerebrospinal fluid (CSF)-barrier. Here we summarise our recent efforts to culture those cells mainly on permeable supports in vitro. Isolated from porcine brains, we report a simple protocol for the primary culture using cytosine arabinoside as an additive that is cytotoxic for other cells except the plexus epithelial cells. Enhanced barrier properties are obtained by withdrawal of serum from the culture medium after confluency is reached. Cells improve their polarity, permeability for hydrophilic substrates is lowered, electrical resistance is increased tenfold, and a pH-gradient is built up across the cell monolayer. Polarised secretion of proteins and most importantly fluid secretion into the apical filter compartment was attained and proven to be dependent on the Na(+),K(+)-ATPase activity. Active transport processes (penicillin G, riboflavin, myo-inositol, ascorbic acid) were studied and clearly showed the involvement of the organic anion transporter. The permeability of the barrier was found to be regulated by cyclic adenosine monophosphate (cAMP). Moreover, we report that cell proliferation and differentiation is controlled by components of the extracellular matrix. The present culture model could now be used as an in vitro system to quantify drug transport across the blood-CSF-barrier.     

Intense beams from gases generated by a permanent magnet ECR ion source at PKU

An electron cyclotron resonance (ECR) ion source is designed for the production of high-current ion beams of various gaseous elements. At the Peking University (PKU), the primary study is focused on developing suitable permanent magnet ECR ion sources (PMECRs) for separated function radio frequency quadrupole (SFRFQ) accelerator and for Peking University Neutron Imaging Facility. Recently, other kinds of high-intensity ion beams are required for new acceleration structure demonstration, simulation of fusion reactor material irradiation, aviation bearing modification, and other applications. So we expanded the ion beam category from O(+), H(+), and D(+) to N(+), Ar(+), and He(+). Up to now, about 120 mA of H(+), 83 mA of D(+), 50 mA of O(+), 63 mA of N(+), 70 mA of Ar(+), and 65 mA of He(+) extracted at 50 kV through a φ 6 mm aperture were produced by the PMECRs at PKU. Their rms emittances are less than 0.2 π?mm?mrad. Tungsten samples were irradiated by H(+) or He(+) beam extracted from this ion source and H∕He holes and bubbles have been observed on the samples. A method to produce a high intensity H∕He mixed beam to study synergistic effect is developed for nuclear material irradiation. To design a He(+) beam injector for coupled radio frequency quadruple and SFRFQ cavity, He(+) beam transmission experiments were carried out on PKU low energy beam transport test bench and the transmission was less than 50%. It indicated that some electrode modifications must be done to decrease the divergence of He(+) beam.     

Differentiation and functions of osteoclasts and odontoclasts in mineralized tissue resorption

The differentiation and functions of osteoclasts (OC) are regulated by osteoblast-derived factors such as receptor activator of NFKB ligand (RANKL) that stimulates OC formation, and a novel secreted member of the TNF receptor superfamily, osteoprotegerin (OPG), that negatively regulates osteoclastogenesis. In examination of the preosteoclast (pOC) culture, pOCs formed without any additives expressed tartrate-resistant acid phosphatase (TRAP), but showed little resorptive activity. pOC treated with RANKL became TRAP-positive OC, which expressed intense vacuolar-type H(+)-ATPase and exhibited prominent resorptive activity. Such effects of RANKL on pOC were completely inhibited by addition of OPG. OPG inhibited ruffled border formation in mature OC and reduced their resorptive activity, and also induced apoptosis of some OC. Although OPG administration significantly reduced trabecular bone loss in the femurs of ovariectomized (OVX) mice, the number of TRAP-positive OC in OPG-administered OVX mice was not significantly decreased. Rather, OPG administration caused the disappearance of ruffled borders and decreased H(+)-ATPase expression in most OC. OPG deficiency causes severe osteoporosis. We also examined RANKL localization and OC induction in periodontal ligament (PDL) during experimental movement of incisors in OPG-deficient mice. Compared to wild-type OPG (+/+) littermates, after force application, TRAP-positive OC were markedly increased in the PDL and alveolar bone was severely destroyed in OPG-deficient mice. In both wild-type and OPG-deficient mice, RANKL expression in osteoblasts and fibroblasts became stronger by force application. These in vitro and in vivo studies suggest that RANKL and OPG are important regulators of not only the terminal differentiation of OC but also their resorptive function. To determine resorptive functions of OC, we further examined the effects of specific inhibitors of H(+)-ATPase, bafilomycin A1, and lysosomal cysteine proteinases (cathepsins), E-64, on the ultrastructure, expression of these enzymes and resorptive functions of cultured OC. In bafilomycin A1-treated cultures, OC lacked ruffled borders, and H(+)-ATPase expression and resorptive activity were significantly diminished. E-64 treatment did not affect the ultrastructure and the expression of enzyme molecules in OC, but significantly reduced resorption lacuna formation, by inhibition of cathepsin activity. Lastly, we examined the expression of H(+)-ATPase, cathepsin K, and matrix metalloproteinase-9 in odontoclasts (OdC) during physiological root resorption in human deciduous teeth, and found that there were no differences in the expression of these molecules between OC and OdC. RANKL was also detected in stromal cells located on resorbing dentine surfaces. This suggests that there is a common mechanism in cellular resorption of mineralized tissues such as bone and teeth.     

Gated‐sted microscopy with subnanosecond pulsed fiber laser for reducing photobleaching

The spatial resolution of a stimulated emission depletion (STED) microscope is theoretically unlimited and practically determined by the signal‐to‐noise ratio. Typically, an increase of the STED beam's power leads to an improvement of the effective resolution. However, this improvement may vanish because an increased STED beam's power is often accompanied by an increased photobleaching, which worsen the effective resolution by reducing the signal strength. A way to lower the photobleaching in pulsed STED (P‐STED) implementations is to reduce the peak intensity lengthening the pulses duration (for a given average STED beam's power). This also leads to a reduction of the fluorophores quenching, thus a reduction of the effective resolution, but the time‐gated detection was proved to be successful in recovering these reductions. Here we demonstrated that a subnanosecond fiber laser beam (pulse width ∼600 ps) reduces the photobleaching with respect to a traditional stretched hundreds picosecond (∼200 ps) beam provided by a Ti:Sapphire laser, without any effective spatial resolution lost.     

Different types of multiple‐synapse boutons in the cerebellar cortex between physically enriched and ataxic mutant mice

Experience‐dependent synapse remodeling is associated with information storage in the nervous system. Neuronal synapses show alteration in various neurological and cognitive disorders in their structure and function. At the ultrastructural level, parallel fiber boutons contacting multiple spines of Purkinje cells in the cerebellar cortex are commonly observed in physiologically enriched animals as well as pathological ataxic mutants. However, the dendritic origin of those spines on parallel fiber multiple‐synapse boutons (MSBs) has been poorly understood. Here, we investigated this issue by 3‐dimensional ultrastructural analysis to determine synaptic connectivity of MSBs in both mice housed in physically enriched environment and cerebellar ataxic mutants. Our results demonstrated that environmental enrichment selectively induced MSBs to contact spines from the same parent dendrite, indicating focal strengthening of synapse through the simultaneous activation of two adjacent spines. In contrast, ataxic mutants displaying impaired motor coordination had significantly more MSBs involving spines originating from different neighboring dendrites compared to both wild‐type and environmentally enriched animals, suggesting that compromising multiple synapse formation may lead to abnormal motor behavior in the mutant mice. These findings propose that environmental stimulation in normal animals mainly involves the refinement of preexisting synaptic networks, whereas pathological ataxic conditions may results from less‐selective but compromising multiple synaptic formation. This study underscores that different types of multiple synapse boutons may have disparate effects on cerebellar synaptic transmission.     

Measuring material softening with nanoscale spatial resolution using heated silicon probes

This article describes the use of heated silicon atomic force microscopy probes to perform local thermal analysis (LTA) of a thin film of polystyrene. The experiments measure film softening behavior with 100 nm spatial resolution, whereas previous research on LTA used probes that had a resolution near 10 microm, which was too large to investigate some types of features. This article demonstrates four methods by which heated silicon probes can perform thermal analysis with nanoscale spatial resolution. The polystyrene softening temperature measured from nanoscale LTA techniques is 120 degrees C, compared to 100 degrees C, measured with bulk ellipsometry. The discrepancy is attributed to the thermal contact resistance at the end of the silicon probe tip, on the order of 10(7)K/W, which modulates heat flow between the tip and sample and governs the fundamental limits of this technique. The use of a silicon probe for LTA enables bulk fabrication, parallelization for high-throughput analysis, and fabrication of a sharp tip capable of nanoscale spatial resolution.     

MRT letter: Nanoscopy of protein colocalization in living cells by STED and GSDIM

We report the use of superresolution fluorescence microscopy for studying the nanoscale distribution of protein colocalization in living mammalian cells. Nanoscale imaging is attained both by a targeted and a stochastic fluorescence on-off switching superresolution method, namely by stimulated emission depletion (STED) and ground state depletion microscopy followed by individual molecular return (GSDIM), respectively. Analysis of protein colocalization is performed by bimolecular fluorescence complementation (BiFC). Specifically, a nonfluorescent fragment of the yellow fluorescent protein Citrine is fused to tubulin while a counterpart nonfluorescent fragment is fused to the microtubulin-associated protein MAP2 such that fluorescence is reconstituted on contact of the fragment-carrying proteins. Images with resolution down to 65 nm prove a powerful new way for studying protein colocalization in living cells at the nanoscale.     

Femtosecond two-photon high-resolution 3D imaging, spatial-volume rendering and microspectral characterization of immunolocalized MHC-II and mLangerin/CD207 antigens in the mouse epidermis

Langerhans cells (LCs) play a sentinel role by initiating both adaptive and innate immune responses to antigens pertinent to the skin. With the discovery of various LCs markers including antibodies to major histocompatibility complex class II (MHC-II) molecules and CD1a, intracellular presence of racket-shaped "Birbeck granules," and very recently Langerin/CD207, LCs can be readily distinguished from other subsets of dendritic cells. Femtosecond two-photon laser scanning microscopy (TPLSM) in recent years has emerged as an alternative to the single photon-excitation based confocal laser scanning microscope (CLSM), particularly for minimally-invasive deep-tissue 3D and 4D vital as well as nonvital biomedical imaging. We have recently combined high resolution two-photon immunofluorescence (using anti MHC-II and Langerin/CD207 antibodies) imaging with microspectroscopy and advanced image-processing/volume-rendering modalities. In this work, we demonstrate the use of this novel state-of-the-art combinational approach to characterize the steady state 3D organization and spectral features of the mouse epidermis, particularly to identify the spatial distribution of LCs. Our findings provide unequivocal direct evidence that, in the mouse epidermis, the MHC-II and mLangerin/CD207 antigens do indeed manifest a high degree of colocalization around the nucleus of the LCs, while in the distal dendritic processes, mLangerin/CD207 antigens are rather sparsely distributed as punctuate structures. This unique possibility to simultaneously visualize high resolution 3D-resolved spatial distributions of two different immuno-reactive antigens, namely MHC-II and mLangerin/CD207, along with the nuclei of LCs and the adjacent epidermal cells can find interesting applications. These could involve aspects associated with pragmatic analysis of the kinetics of LCs migration as a function of immuno-dermatological responses during (1) human Immunodeficiency virus disease progression, (2) vaccination and targeted gene therapy, (3) skin transplantation/plastic surgery, (4) ultraviolet and other radiation exposure, (5) tissue-engineering of 3D skin constructs, as well as in (6) cosmetic industry, to unravel the influence of cosmeceuticals.     

氦离子显微镜：技术和应用进展

氦离子显微镜能够提供所有扫描射线法中最高空间分辨率的表面图像,以及极高的表面灵敏度。这些因素结合起来,能提供纳米级的无与伦比的样品信息。结合这种工具独特的充电控制技术,一些应用问题可以得到解决。本文介绍了一些近期的结果。例如,生命科学影像往往依赖于研究高度绝缘的轻型有机材料的表面形貌。氦离子显微镜无需导电涂层就可以提供极好的成像。诸如生物工程学研究之类的应用,可同时受益于充电控制和氦离子成像可避免电子束辐射造成损伤的优点。可以使用氦离子显微镜进行离子散射能谱分析,从而将这项灵敏度最高的表面技术应用于同时要求具有空间分辨率的分析任务中。氦离子显微镜也用于表面和材料的图形化。这对于创建和表征纳米级的新特性是至关重要的。     

Application of photoconversion technique for correlated confocal and ultrastructural studies in organotypic slice cultures

Photoconversion of fluorescent staining into stable diaminobenzidine (DAB) precipitate is widely used for neuroanatomical and developmental studies. An important advantage of the approach is to make correlations between light and electron microscopy analyses possible, the DAB reaction product formed during photoconversion being electron dense. By combining a photoconversion approach with biolistic transfection of neurons in organotypic hippocampal slice cultures, we describe here a methodology that allowed us to study at the electron microscopy level the fine details of cells expressing specific genes of interest. The same approach has also been used to analyze the ultrastructural characteristics of specific cells such as neurons recorded with patch clamp techniques. This approach revealed particularly useful for studies of dendritic arborisation, dendritic spines, and axon varicosities of identified cells, as precise morphometric parameters of these structures can only be obtained by electron microscopy. The techniques used for fluorescent staining and photoconversion of these different cell structures and the results obtained by electron microscopic analyses are described.     

Ultrastructural description of glutamate-, aspartate-, taurine-, and glycine-like immunoreactive terminals from five rat brain regions

The ultrastructural localization of putative excitatory (glutamate, aspartate) and inhibitory (taurine, glycine) amino acid neurotransmitters is described in several selected rat brain regions. In general, axon terminal profiles immunoreactive for excitatory amino acids formed asymmetric synapses with non-immunoreactive small diameter dendritic profiles or dendritic spines. In the cerebellum, both mossy fiber terminals and parallel fiber terminals were immunoreactive for glutamate and aspartate. In the hippocampus, mossy fiber terminals within the stratum lucidum of the CA3 region were immunoreactive for glutamate. Localization of glutamate and aspartate to cerebellar parallel and mossy fibers, as well as the identification of glutamate in hippocampal mossy fibers, is consistent with the excitatory nature of these fibers as described in previous physiological studies. Glutamate-like immunoreactive terminals were also identified in subnucleus caudalis of the spinal trigeminal nucleus and in the dorsal horn of the spinal cord. Immunoreactive axon terminals for two putative inhibitory neurotransmitters, glycine and taurine, displayed a greater number of morphological variations in synaptic structure. In the cerebellum, taurine-like immunoreactivity was present in both basket cell axon terminals which formed symmetric synapses with Purkinje cell neurons, and in a few mossy fiber terminals which formed asymmetric synapses with dendritic spines. In the area dentata of the hippocampus, taurine-like immunoreactive profiles formed asymmetric synapses with dendritic elements. Glycine-like immunoreactive terminals formed symmetric synapses with cell perikarya in both the ventral horn of the spinal cord and in the cochlear nuclei, and on axon terminals in the spinal trigeminal and cochlear nuclei. In contrast, some glycine-like immunoreactive terminals formed asymmetric synapses with distal dendritic profiles in the spinal cord and spinal trigeminal nucleus. The localization of taurine to cerebellar basket cell axons and glycine to axon terminals that synapse on ventral horn motor neuron perikarya is consistent with the hypothesis that these amino acids are functioning as inhibitory neurotransmitters at these synapses. Taurine localization to cerebellar mossy fibers and to fibers in the molecular layer of the dentate gyrus may be more consistent with a proposed neuromodulator role of taurine.     

A protocol for single-source dual-pulse stimulated emission depletion setup with Bessel modulation

STimulated Emission Depletion (STED) microscopy attains super-resolution in biological imaging beyond the diffraction limit. Here, we give a concise protocol to construct a dual-pulse STED setup with one super-continuum laser. Moreover, a flexible and dismountable Bessel modulation module is introduced for potential 2D-stack STED imaging. Experiments and notices are introduced in detail, with discussion on some important check-points for STED, such as detector saturation. Finally, the results validate the system working.     

受激发射损耗显微术及其在生物医学上的应用

由于受到光学衍射的限制,均匀照明宽视场荧光显微术和激光共焦扫描显微术的分辨率约为200～300nm。近年来受激发射损耗显微术在突破衍射极限以及应用方面取得许多令人瞩目的成果。本文简要介绍受激发射损耗显微术的原理、方法及其在生物医学上的应用。     

Cryo-X-ray analysis-A novel tool to better understand the physicochemical reactions at the bioglass/biological fluid interface

The present study deals with the short-term physicochemical reactions at the interface between bioactive glass particles [55SiO(2)-20CaO-9P(2)O(5)-12Na(2)O-4MgO. mol%] and biological fluid (Dulbecco Modified Eagle's Medium (DMEM)). The physicochemical reactions within the interface are characterized by scanning transmission electron microscopy (TEM) (STEM) associated with Energy-dispersive X-ray spectroscopy (EDXS). Microanalysis of diffusible ions such as sodium, potassium, or oxygen requires a special care. In the present investigation the cryo-technique was adopted as a suitable tool for the specimen preparation and characterization. Cryosectioning is essential for preserving the native distribution of ions so that meaningful information about the local concentrations can be obtained by elemental microanalysis. The bioglass particles immersed in biological fluid for 24 h revealed five reaction stages: (i) dealkalization of the surface by cationic exchange (Na(+), Ca(2+) with H(+) or H(3)O(+)); (ii) loss of soluble silica in the form of Si(OH)(4) to the solution resulting from the breakdown of Si--O--Si bonds (iii); repolymerization of Si(OH)(4) leading to condensation of SiO(2)); (iv) migration of Ca(2+) and PO(4) (3-) to the surface through the SiO(2)-rich layer to form CaO-P(2)O(5) film; (v) crystallization of the amorphous CaO-P(2)O(5) by incorporating OH-- or CO(3) (2-) anions with the formation of three different surface layers on the bioactive glass periphery. The thickness of each layer is approximately 300 nm and from the inner part to the periphery they consist of Si--OH, which permits the diffusion of Ca(2+) and PO(4) (3-) ions and the formation of the middle Ca--P layer, and finally the outer layer composed of Na--O, which acts as an ion exchange layer between Na(+) ions and H(+) or H(3)O(+) from the solution.     

Effect of montmorillonite organic modification on microstructures and ultraviolet aging properties of bitumen

The effect of montmorillonite (MMT) organic modification on microstructures and ultraviolet (UV) aging properties of bitumen was investigated. The microstructures of MMT modified bitumen were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and atomic force microscopy (AFM), respectively. The binders were aged by UV radiation. The UV aging properties of MMT modified bitumen was studied by determining physical properties and AFM analysis. XRD and FTIR analyses show that the sodium montmorillonite (Na(+) -MMT) modified bitumen forms a phase-separated structure, whereas the organo-montmorillonite (OMMT) modified bitumen forms an intercalated structure. After Na(+) -MMT modification, the contrast between the matrix and the dispersed domains is inverted according to AFM analysis. However, this contrast inversion is prevented with the introduction of OMMT due to the good compatibility between the OMMT and the bitumen. As a result of UV aging, both viscosity aging index and softening point increment of OMMT modified bitumen are lower than that of the unmodified bitumen and Na(+) -MMT modified bitumen. Furthermore, the association interactions and single-phase trend in OMMT modified bitumen are further prevented in comparison with Na(+) -MMT modified bitumen during UV aging, indicating the good aging resistance of OMMT modified bitumen after organic modification of MMT.     

Surface roughness and texture analysis in microscale

The capacity of various instruments in roughness measurements and analysis is compared. Review of various models of roughness is made and the models of contact mechanics are presented, when taking account the nanometer scale roughness and relating phenomena of adhesion and surface forces. The concept of multi-level models of roughness and contact area is presented. Analysis of surface topography as a spatial pattern is given, when using the approaches of image recognition theory operating with the 3D digital images processing. Qualitatively the spatial structure is often characterized in terms of texture features such as random, linear, wavy etc., and some national standards introduce spatial structure of machined surfaces. However, texture characteristics are not adequately investigated. AFM images of different surfaces were used as initial data and multi-dimensional scaling technique was used for the data analysis. The study has shown that there are at least four types surface textures on nanoscale level. The correlation was found between texture types and reasons of their formation.