Cheek Cells Research Articles

AIR BUBBLE ENCAPSULATION OF EUKARYOTIC CELLS AND THERAPY FAILURES

Background: The purpose of this manuscript is to introduce a newly discovered potential dangers of air bubbles used for therapeutic or diagnostic purposes into the human body.At present, the injection of air bubbles into the human body for diagnostic purpose is viewed positively by the medical/scientific community. In Vitro experiments are presented whereby cells isolation by air bubbles could interfere with chemotherapy treatments.Methods: Author’s own saliva sample was spitted out onto the center of a clean 25X75x1mm glass slide. The sample was placed and focused on the viewing platform of a video microscope. A toothpick was used to harvest inner cheek cells and gently transfer onto the spitted out sample. After focusing, areas were selected showing floating cells and air bubbles. Different laminar levels were observed by cells migrating at different levels.While microscopically observing the sample, the glass slide was disturbed by finger tapping, the aim to induce bubble bursting.Results: Deformed cells were observed when adhering to the outer surface of air bubbles. Additionally, undeformed cells seen at two distinct perpendicular layers when trapped within the floating bubbles. Noticed was a selective attraction of cells by the outer edge of the floating bubbles. Cells attached to the bubble’s edge were being deformed and attracted to each other. Cells were also observed passing unattracted when in a separate laminar flow under the floating bubble. The provocative tapping causing air bubbles to cavitate and burst.Conclusions: The bursting of an air bubble is not the only factor in floating eukaryotic cells deformation. In this manuscript video microscopy and still images are introduced demonstrating a newly found horizontal flat parallel energy field in the periphery of the oxygen bubble. This energy is evident in the free-floating air bubble interface as cheek eukaryotic cells adhere only to the flat round edge of a bubble. Cells are attracted, adhered to each other, and deformed by their own intrinsic attraction. Once the bubble bursts, cells and debris are dispersed, with cells adherence partially disturbed. Cell deformations persisting. It could be hypothesized that cancer cells trapped at different laminar layers inside the bubble be refractory to external chemotherapy agents thus retaining their cancer characteristics.

Structured illumination contrast transfer function for high resolution quantitative phase imaging.

We report a sub-diffraction resolution imaging of non-fluorescent samples through quantitative phase imaging. This is achieved through a novel application of structured illumination microscopy (SIM), a super-resolution imaging technique established primarily for fluorescence microscopy. Utilizing our contrast transfer function formalism with SIM, we extract the high spatial frequency components of the phase profile from the defocused intensity images, enabling the reconstruction of a quantitative phase image with a frequency spectrum that surpasses the diffraction limit imposed by the imaging system. Our approach offers several advantages including a deterministic, phase-unwrapping-free algorithm and an easily implementable, non-interferometric setup. We validate the proposed technique for high-resolution phase imaging through both simulation and experimental results, demonstrating a two-fold enhancement in resolution. A lateral resolution of 0.814 µm is achieved for the phase imaging of human cheek cells using a 0.42 NA objective lens and an illumination wavelength of 660 nm, highlighting the efficacy of our approach for high-resolution quantitative phase imaging.

Genetic and Phenotypic Variations in Phenylthiocarbamide Bitter Taste Receptors in Iraqi Population

Bitter substances are identified by protein receptors located on surface of taste cell membranes. Mutational polymorphism of the bitter taste receptor (TAS2R38) is a significant determinant in phenylthiocarbamide (PTC) threshold perception. This research's objectives were to find TAS2R38 polymorphisms in Iraqi people and investigate any correlations between genotype and the PTC taste sensitivity. Bitterness sensitivity was determined by assessing the capacity to differentiate and the responsiveness to a representative strip of PTC. Cheek cells samples were collected for DNA extraction, PCR amplification and genotyping. PCR was performed to amplify the short region of the TAS2R38 gene containing the initial polymorphisms of interest (145G > C, rs713598). Amplified samples were digested by the restriction enzyme (HaeIII) to study the genetic variations in TAS2R38 which is involved in PTC bitter sensitivity. This particular study included a total of 32 different cohorts. The phenotypic frequency of PTC strong-tasters and non-tasters was identical at 34.375% which was a greater value than the frequency of weak-tasters (31.25%). While genotypic data analysis showed that weak-tasters had a genotypic frequency of 45.16% which was higher than the genotypic frequencies of strong-taters (22.58%) and non-tasters (32.26%) respectively. In addition to this, 87.1% of the projected phenotypic and genotypic frequencies were in agreement with one another. Even though more detailed statistical analysis with a bigger group is needed. The results of this study suggest that allelic variation in the single locus TAS2R38 rs713598 works as a crucial genetic marker for bitterness sensitivity and has vital roles in the bitter tasting ability among Iraqi population.

Characterisation of topographical, biomechanical and maturation properties of corneocytes with respect to anatomical location.

The Stratum Corneum (SC) is the first barrier of the skin. The properties of individual cells are crucial in understanding how the SC at different anatomical regions maintains a healthy mechanical barrier. The aim of the current study is to present a comprehensive description of the maturation and mechanical properties of superficial corneocytes at different anatomical sites in the nominal dry state. Corneocytes were collected from five anatomical sites: forearm, cheek, neck, sacrum and medial heel of 10 healthy young participants. The surface topography was analysed using Atomic Force Microscopy (AFM) and Scanning Electron Microscopy (SEM). The level of positive-involucrin cornified envelopes (CEs) and desmoglein-1 (Dsg1) were used as indirect measures of immature CEs and corneodesmosomes, respectively. In addition, AFM nanoindentation and stress-relaxation experiments were performed to characterise the mechanical properties. Volar forearm, neck and sacrum corneocytes presented similar topographies (ridges and valleys) and levels of Dsg1 (13-37%). In contrast, cheek cells exhibited circular nano-objects, while medial heel cells were characterized by villi-like structures. Additionally, medial heel samples also showed the greatest level of immature CEs (32-56%, p<0.001) and Dsg1 (59-78%, p<0.001). A large degree of inter-subject variability was found for the Young's moduli of the cells (0.19-2.03GPa), which was correlated with the level of immature CEs at the cheek, neck and sacrum (p<0.05). It is concluded that a comprehensive study of the mechanical and maturation properties of corneocytes may be used to understand the barrier functions of the SC at different anatomical sites.

Single-shot experimental-numerical twin-image removal in lensless digital holographic microscopy

Lensless digital holographic microscopy (LDHM) offers very large field of view label-free imaging crucial, e.g., in high-throughput particle tracking and biomedical examination of cells and tissues. Compact layouts promote point-of-case and out-of-laboratory applications. The LDHM, based on the Gabor in-line holographic principle, is inherently spoiled by the twin-image effect, which complicates the quantitative analysis of reconstructed phase and amplitude maps. Popular family of solutions consists of numerical methods, which tend to minimize twin-image upon iterative process based on data redundancy. Additional hologram recordings are needed, and final results heavily depend on the algorithmic parameters, however. In this contribution we present a novel single-shot experimental-numerical twin-image removal technique for LDHM. It leverages two-source off-axis hologram recording deploying simple fiber splitter. Additionally, we introduce a novel phase retrieval numerical algorithm specifically tailored to the acquired holograms, that provides twin-image-free reconstruction without compromising the resolution. We quantitatively and qualitatively verify proposed method employing phase test target and cheek cells biosample. The results demonstrate that the proposed technique enables low-cost compact LDHM imaging with enhanced precision, achieved through the elimination of twin-image errors. This advancement opens new avenues for more accurate technical and biomedical imaging applications using LDHM, particularly in scenarios where cost-effective and portable imaging solutions are desired.

Common-path quantitative phase imaging by propagation through a sinusoidal intensity mask

We present a new quantitative approach for phase retrieval that is derived from the analysis of light intensity propagation through a phase object and a sinusoidal intensity mask positioned into the light path. Unlike the Transport of Intensity Equation (TIE), we deduce a new algorithm that results in a simpler expression since it does not include the Laplacian of the phase. In practice, the method is implemented in a common path optics where each optical component of the assembly remains fixed and phase unwrapping is not required. We introduce the analytical expressions for this algorithm and show experimental results including the phase retrieval of a phase object and of cheek cell samples.

DNA isolation at a distance: Undergraduate experiential learning to create a virtual elementary outreach program.

The COVID-19 pandemic has transformed the realities of science education, and the move to remote learning has made laboratory instruction particularly challenging. Extensive efforts have been made to design virtual labs,1, 2 including efforts to create at-home wet lab experiments.3 In addition to remote wet labs, we experienced an additional challenge: continuing our elementary outreach program. Each year we host a STEM outreach for several hundred local students. Undergraduates help guide elementary students through an activity isolating their own DNA from cheek cells. To address the need for remote labs and to continue our elementary outreach program, we united the two in a virtual experiential learning approach. Undergraduate students, faculty, and instructional design staff worked collaboratively to create an interactive video of DNA isolation and a YouTube channel, SciKids Network, to share the digital content. Experiential outreach opportunities improve academic performance and STEM enthusiasm in both elementary students4, 5 and their undergraduate mentors.6, 7 With the suspension of our outreach program, we sought to continue this valuable experience through a virtual format. Working collaboratively, undergraduate students adapted the lab-based DNA isolation protocol to a version that could be easily performed at home. They converted metric units to US customary units, and identified reagents and equipment commonly available in a kitchen. Students learned how to trouble-shoot as they independently iterated through the protocol. After finalizing the at-home method (Figure 1a), students filmed themselves performing the protocol using smartphones or other devices. They provided age-appropriate commentary and instructions for their elementary audience. Student film clips were edited together into a single, cohesive video for the elementary audience. We used Adobe Premiere and Adobe Illustrator to create the final video, adding visual and auditory aids to improve the clarity of instructions and engagement. Three major goals for the outreach video were to: (1) make science fun and accessible, (2) teach the concept of DNA through a hands-on activity, and (3) create an inclusive experience for elementary students. By compiling many students' clips, we sought to celebrate diversity and show elementary students that everyone can be a scientist (Figure 1b). Studies have demonstrated that early intervention in elementary students' perception of scientists can increase enthusiasm and participation in STEM, particularly for underrepresented groups.8 Our pre-pandemic outreach program was geographically limited to local schools, and the move to a virtual format created the opportunity to reach a broader audience. To share the video, we developed a new YouTube channel, SciKids Network (Figure 1c, https://www.youtube.com/channel/UCU23sXeFXVm98ScDcXRAmbA), hosted by our institution. We will continue to create biology content for the channel, as well as broaden the scope to other STEM fields. While remote learning has been challenging, it stimulated us to develop a digital outreach platform that connects with a larger audience, offers more equitable access to learning opportunities, and is primed for future growth of content to promote STEM literacy. We would like to thank the students who created the video content: Pablo Reina-Gonzalez, Emnet Sisay, and Shelby McVey. We would like to thank our instructional designer, Sacharja Cunningham for his support with software and the channel creation and our graphic designer, Brad Lewthwaite for his logo designs for SciKids network, as well as Hamilton College LITS and Communications departments. Our project was supported by the Social Innovation and Transformational Leadership Grant from the Hamilton College Arthur Levitt Public Affairs Center and by the National Science Foundation: grant MCB-1925546.

EXAMINATION OF THE EFFECT OF SMOKING ON CHEEK CELLS AT A MICROSCOPIC LEVEL

Oral cancer is lifestyle-related cancer, with the consumption of tobacco as a primary factor. The purpose of this study is to determine the impact of smoking on the cheek cells of an individual, using scrapings containing exfoliated buccal cells to correlate the microscopic ndings and observations with the period for which each participant smoked and the frequency of their consumption of tobacco. The association between cells showcasing alterations and indication of buccal mucosa cancer with an abnormally large nucleus to cytoplasm ratio and the time period for which the respective participant has been exposed to smoking is examined. Behaviour intervention to quit smoking may be accelerated if the global public is made aware of risk factors for developing cancer of oral mucosa. Thus, proving the need for increased research on the same.

Holographic point source for digital lensless holographic microscopy.

A holographic point source (HPS) developed for digital lensless holographic microscopy (HPS-DLHM) is presented. The HPS is an off-axis phase transmission hologram of an experimental micrometer pinhole recorded on a photopolymer holographic film. An amplitude division interferometer, adjusted to operate at maximum diffraction efficiency, has been employed to record the hologram. The results of HPS-DLHM have been contrasted with the results obtained via conventional DLHM, and the two techniques were found to give similar measurements. Compared with conventional pinhole-based DLHM illumination, our cost-effective proposal provides increased mechanical stability, the possibility of wider spherical illumination cones, and shorter reconstruction distances. These superior features pave the way to applying this quantitative phase imaging (QPI) technique in biomedical and telemedicine applications. The imaging capabilities of our HPS-DLHM proposal have been tested by using an intricate sample of a honeybee leg, a low-absorption sample of epithelial cheek cells, a 1951 USAF test target, and smeared human erythrocytes.

Crossing unlikely paths in science.

Crossing unlikely paths in science.

Infant Formula Supplemented With Milk Fat Globule Membrane, Long-Chain Polyunsaturated Fatty Acids, and Synbiotics Is Associated With Neurocognitive Function and Brain Structure of Healthy Children Aged 6 Years: The COGNIS Study.

BackgroundAdequate nutrient intake during the first few months of life plays a critical role on brain structure and function development.ObjectivesTo analyze the long-term effects of an experimental infant formula (EF) on neurocognitive function and brain structure in healthy children aged 6 years compared to those fed with a standard infant formula or breastfed.MethodsThe current study involved 108 healthy children aged 6 years and participating in the COGNIS Study. At 0–2 months, infants were randomized to receive up to 18 months of life a standard infant formula (SF) or EF enriched with milk fat globule membrane (MFGM), long-chain polyunsaturated fatty acids (LC-PUFAs) and synbiotics. Furthermore, a reference group of breastfed (BF) infants were also recruited. Children were assessed using neurocognitive tests and structural Magnetic Resonance Imaging (MRI) at 6 years old.ResultsExperimental infant formula (EF) children showed greater volumes in the left orbital cortex, higher vocabulary scores and IQ, and better performance in an attention task than BF children. EF children also presented greater volumes in parietal regions than SF kids. Additionally, greater cortical thickness in the insular, parietal, and temporal areas were found in children from the EF group than those fed with SF or BF groups. Further correlation analyses suggest that higher volumes and cortical thickness of different parietal and frontal regions are associated with better cognitive development in terms of language (verbal comprehension) and executive function (working memory). Finally, arachidonic acid (ARA), adrenic acid (AdA), docosahexaenoic acid (DHA) levels in cheek cell glycerophospholipids, ARA/DHA ratio, and protein, fatty acid, and mineral intake during the first 18 months of life seem to be associated with changes in the brain structures at 6 years old.ConclusionsSupplemented infant formula with MFGM components, LC-PUFAs, and synbiotics seems to be associated to long-term effects on neurocognitive development and brain structure in children at 6 years old.Clinical Trial Registrationhttps://www.clinicaltrials.gov/, identifier: NCT02094547.

All-fiber negative axicon probe with a Bessel beam for cellular-level low coherence phase microscopy and refractive index measurement.

We demonstrate an all-fiber negative axicon probe with a Bessel beam for low coherence phase microscopy including refractive index measurement of a cellular level sample in reflection mode. The negative axicon chemically incised at the distal end of the optical fiber spawns the Bessel beam. The system provides a phase sensitivity of ∼0.28 mrad and optical path length sensitivity of ∼23 pm in air. The lateral resolution and working distance are found to be ∼3.91 µm and 650 µm to exhibit the performance of the system experimentally. The three-dimensional (3D) phase map of the cheek cell along with the refractive index is obtained from the reflected power spectrum. The combined low coherence phase microscopy and refractive index measurement provides the system with a potential for biological application. Also, the all-fiber probe can be easily integrated as an endoscopic probe.

Phase imaging microscopy under the Gabor regime in a minimally modified regular bright-field microscope

Quantitative phase imaging (QPI) is nowadays a powerful tool for visualization and analysis of biological processes. QPI is usually attained from specifically designed optical microscopes retrieving phase information in a quantitative way. In this paper we report on an extremely simple, low cost and compact way to update a standard bright-field microscope with coherent sensing capabilities. It is based on the in-line Gabor holography concept and only needs to replace the illumination broadband source of the regular microscope with a coherent one. The proposed methodology is completed by the recording of a digital in-line Gabor hologram instead of regular imaging conditions and by the numerical processing of the recorded hologram to finally achieve QPI. The selection of the defocus distance is critical to finally achieve high quality phase imaging, so calibration considering phase and amplitude test targets is presented for the proper definition of such defocus distance. In addition, the selected configuration is experimentally validated using different samples (microbeads, cheek cells and alive spermatozoa). All the experiments are implemented in a regular Olympus BX-60 upright microscope using a 20X 0.46NA objective lens. The proposed method shows how to convert a regular microscope into a holographic one with probably the minimum needed modifications and with the main limitation coming from the Gabor imaging conditions (weak diffractive samples and twin image presence).

Single shot quantitative phase gradient estimation using Wigner-Ville distribution in digital holographic microscopy

In digital holographic microscopy, direct measurement of phase gradient is commonly required for investigations pertaining to cell morphology and feature detection. In this paper, we present the application of the Wigner-Ville distribution method for single shot quantitative phase gradient measurement in digital holographic microscopy. The method allows simultaneous extraction of phase derivatives along the horizontal and vertical dimensions to compute the phase gradient without the need of multiple images, filtering operations, or specialized experimental setups. Experimental results for imaging onion and cheek cells and standard calibration target, validates the potential of the proposed approach in digital holographic microscopy.

Quality-Controlled Sputum Analysis by Flow Cytometry.

Sputum, widely used to study the cellular content and other microenvironmental features to understand the health of the lung, is traditionally analyzed using cytology-based methodologies. Its utility is limited because reading the slides is time-consuming and requires highly specialized personnel. Moreover, extensive debris and the presence of too many squamous epithelial cells (SECs), or cheek cells, often renders a sample inadequate for diagnosis. In contrast, flow cytometry allows for high-throughput phenotyping of cellular populations while simultaneously excluding debris and SECs. The protocol presented here describes an efficient method to dissociate sputum into a single cell suspension, antibody stain and fix cellular populations, and acquire samples on a flow cytometric platform. A gating strategy that describes the exclusion of debris, dead cells (including SECs) and cell doublets is presented here. Further, this work also explains how to analyze viable, single sputum cells based on a cluster of differentiation (CD)45 positive and negative populations to characterize hematopoietic and epithelial lineage subsets. A quality control measure is also provided by identifying lung-specific macrophages as evidence that a sample is derived from the lung and is not saliva. Finally, it has been demonstrated that this method can be applied to different cytometric platforms by providing sputum profiles from the same patient analyzed on three flow cytometers; Navios EX, LSR II, and Lyric. Furthermore, this protocol can be modified to include additional cellular markers of interest. A method to analyze an entire sputum sample on a flow cytometric platform is presented here that makes sputum amenable for developing high-throughput diagnostics of lung disease.

Biomonitoring of children and adolescents using orthodontic appliances made of acrylic resins through micronucleus testing of exfoliated buccal and palatal mucosa cells

The present study aimed to investigate the occurrence of micronuclei and the degenerative nuclear alterations indicative of apoptosis and necrosis in the exfoliated buccal and palatal mucosa cells of children and adolescents using orthodontic appliances made of self-curing acrylic resins. The micronuclei and nuclear alterations were evaluated in a minimum of 2000cellscollected from the cheeks and palates of 30 patients of both sexes, aged between 6 and 12years. The cell evaluations were performed before appliance installation and 15 to 21days after installation. A conditional test was used. In all analyses, the significance level was 5%. No differences in the occurrence of micronuclei or the nuclear degenerative changes indicative of apoptosis and necrosis were observed in the cheek cells between the 2 time points (P>0.05). However, evaluation of the palate cells revealed a significant increase in the occurrence of micronuclei and the nuclear alterations indicative of apoptosis (P<0.01) but not of karyolysis (P>0.05). Direct contact of orthodontic appliances made of acrylic resins with the oral mucosa increases the incidence of chromosomal damage and degenerative nuclear alterations.

LEP and LEPR Polymorphisms Influences Anthropometric Outcome in Response to 8 Weeks of Combined Training in Obese boys

Objectives: The purpose of the present study was to investigate whether LEP19 G&gt;A and LEPR 668 A&gt;G polymorphisms, would influence the effect of an 8-week combined aerobic and resistance training.&#x0D; Methods: Thirty obese boys (BMIz&gt;+2) aged 11-13 (12.66±0.47) were recruited from three middle schools in Quchan. The changes in body composition parameters and metabolic factors in response to 8-weeks combined aerobic and resistance training program were analyzed regarding LEP and LEPR polymorphism. DNA was extracted from cheek cells donated by the 30 participants and genotyping was carried out using PCR.&#x0D; Results: Our results suggest that carriers of rs2167270G allele and rs1137101A allele were characterized by a greater reduction in body mass and WHR (P&lt; 0.05). Also, a significant decrease was observed in leptin levels in carriers of rs2167270G allele after the training program (P=0.031). Moreover, the LEP and LEPR polymorphisms were associated with changes in lipid profile in response to training.&#x0D; Conclusion: In response to 8 weeks of regular physical activity, obese boys with G (rs2167270) and A (rs1137101) alleles had the best likelihood of losing weight which was associated with a decrease in body mass, fat mass (%), WHR and leptin concentrations.

Epigenetic Age Acceleration and Risk for Posttraumatic Stress Disorder following Exposure to Substantiated Child Maltreatment

ABSTRACT Objective: Child maltreatment is among the strongest predictors of posttraumatic stress disorder (PTSD). However, less than 40% of children who have been maltreated are ever diagnosed with PTSD, suggesting that exposure to child maltreatment alone is insufficient to explain this risk. This study examined whether epigenetic age acceleration, a stress-sensitive biomarker derived from DNA methylation, explains variation in PTSD diagnostic status subsequent to child maltreatment. Method: Children and adolescents (N = 70; 65.7% female), 8–15 years of age (M = 12.00, SD = 2.37) and exposed to substantiated child maltreatment within the 12 months prior to study entry, were enrolled. Participants provided epithelial cheek cells via buccal swab for genotyping and quantification of epigenetic age acceleration within a case-control design. PTSD diagnostic status was determined using the Child PTSD Symptoms Scale according to the DSM-IV-TR algorithm. Results: Epigenetic age acceleration predicted current PTSD status, revealing an effect size magnitude in the moderate range, OR = 2.35, 95% CI: 1.22– 4.51, after adjusting for sample demographics, polygenic risk for PTSD, and lifetime exposure to other childhood adversities. Supplemental analyses demonstrated that epigenetic age acceleration was related to a greater severity of PTSD arousal symptoms (r =.29, p =.015). There were no differential effects for child maltreatment subtype on epigenetic age acceleration or PTSD status. Conclusions: The biological embedding of child maltreatment may explain variation in PTSD diagnostic status and serve as a novel approach for informing selective prevention or precision-based therapeutics for those at risk for PTSD.

Using the Integrated Genome Viewer to reveal amplicon-derived polymorphism enriched at the phenylthiocarbamide locus in the teaching lab.

Due to its distinct phenotype and relatively simple inheritance pattern, the phenylthiocarbamide (PTC) loci is frequently utilized in teaching laboratories to demonstrate genetic concepts such as Mendelian inheritance and population genetics. We have developed a next-generation sequencing and bioinformatics approach to analyze the PTC gene locus to reveal single nucleotide polymorphism (SNP) variation at nucleotide position 785 that predicts tasting ability in humans. Here students purify DNA from their own cheek cells, perform polymerase chain reaction (PCR) amplification of the PTC gene followed by cleaved amplified polymorphic sequence (CAPS) testing. Students perform a second PCR on the PTC loci using high-fidelity Taq to create bar-coded amplicons for next-generation sequencing on the Ion Torrent Personal Genome Machine. Bioinformatic verification reveals polymorphic variation by aligning the entire class PTC PCR fragment sequence to the human gene using Bowtie2 and visualizing the results in the Integrated Genome Viewer. This exercise presents a learning opportunity for students to use next-generation sequencing to predict their own PTC taste sensitivity phenotype coupled with the standard CAPS method. This approach brings the PTC teaching method into the genomics era.

Open-source, cost-effective, portable, 3D-printed digital lensless holographic microscope.

In this work, the design, construction, and testing of the most cost-effective digital lensless holographic microscope to date are presented. The architecture of digital lensless holographic microscopy (DLHM) is built by means of a 3D-printed setup and utilizing off-the-shelf materials to produce a DLHM microscope costing US$52.82. For the processing of the recorded in-line holograms, an open-source software specifically developed to process this type of recordings is utilized. The presented DLHM setup has all the degrees of freedom needed to achieve different fields of view, levels of spatial resolution, and 2D scanning of the sample. The feasibility of the presented platform is tested by imaging non-bio and bio samples; the resolution test targets, a section of the head of a Drosophila melanogaster fly, red blood cells, and cheek cells are imaged on the built microscope.