Tape Transfer Research Articles

BIO10: Novel Method of Extracorporeal Membrane Oxygenator Histology

Background: Despite systemic anticoagulation, loss of function of the artificial lung (e.g., oxygenator) remains common. Moreover, the exchange of these artificial organs can be life-threatening as they interrupt continuous support. Current research suggests that cellular activation leading to thrombosis, cellular debris, or hollow-fiber breakdown may be cause of circuit occlusion. The purpose of this study is to develop a method to quantify cellular deposition to determine the source of oxygenator failure. Methods: Seven Getinge Quadrox-iD and one Medtronic Nautilus oxygenators were collected after component failure. Oxygenators were rinsed with saline, fixed with an ethanol-based solution and frozen for processing. The oxygenators were then dissected, and oxygenator fibers were sampled randomly from the inlet surface. Samples were imbedded in an optimum cutting temperature compound, frozen, sliced to 25 mm sections and mounted using a novel ultraviolet tape transfer system. Nucleated cells, fibrinogen, platelets, and proteins for DNA expression (Histone 3) and clot initiation (tissue factor) were stained using immunofluorescence. A square-root transformation was used to normalize all the fluorescence data. Results: There was no difference in gross cell deposition or clot between the Getinge or Medtronic oxygenators. The average nucleated cell count was 102 (min: 4.00; max 546) surrounding a cross-section of an oxygenator hollow-fiber. Fibrinogen deposition was increased in distal sections compared to sections obtained closer to the blood inlet (p < 0.01). Histone 3 was also increased in the distal sections compared to sections closer to the blood inlet (p < 0.03). Tissue factor expression was greater in the oxygenators obtained from patients on venovenous compared to venoarterial support (p < 0.03). Conclusion: Improving understanding of oxygenator failure needs protocolized assessments of the hollow fibers that provide gas exchange. This method of dissection maintains the architecture of the hollow-fiber providing reproducible cellular deposition data and the opportunity for multiple modes of analysis. Quantitative histological evaluation of oxygenator membranes may provide important information to evaluate novel coatings and anticoagulants.Figure 1. Immunofluorescent stain of hollow fiber oxygenator tube with cellular deposition. Leukocytes stained with blue (DAPI), fibrinogen stained green, and platelets (CD61) stained red.

Abstract 5646: Spatial transcriptomic profiling of the human and mouse retina prepared with CryoJane Tape Transfer System using GeoMx and CosMx spatial analysis

Abstract The goal of this study is to identify key transcriptomic markers within layers of the retina by individually profiling layers using cellular and subcellular spatial transcriptomics, additionally, comparing the results between each level. Both human and mouse retina samples, prepared fresh frozen and fixed frozen, are analyzed using the GeoMx® Digital Spatial Profiler (DSP) and CosMx® Spatial Molecular Imager (SMI) using the whole mouse transcriptome atlas and 1000-plex mouse neuro panel, respectively. Samples are fixed using Cryo-Jane Taper Transfer system. Samples are mounted on to adhesive coated slides as well as adhesive tape to mount samples to glass slides. This method is used to secure fragile frozen tissue, such as the retina. Human and mouse samples were stained using immunofluorescent microscopy targeting neurofilament H (NF-H), glial fibrillary acidic protein (GFAP) and NeuN on DSP and 18s rRNA, amyloid-beta and GFAP on SMI. Staining allows for identification of structural layers in the retina. Simultaneously, regions of interest (ROI) for spatial profiling are selected based on immunofluorescent stains. On DSP, each sample had 3x ROIs in the photoreceptor layer, inner nuclear layer and ganglion cell layer, then, oligonucleotides were collected and sequenced. Finally, raw counts were Q3 normalized for analysis. For SMI data analysis, 6 field of views (FOVs) were put on each section to cover most regions with multiple layers. ~8000 genes were detected on human retina samples using DSP. Around 500 unique genes were detected between the photoreceptor and inner nuclear layer using DSP. Preliminary SMI results show we were able to identify cell types (amacrine, horizontal cell, biopolar cell, ganglion cell, etc) and cell specific markers for outer nuclear layer, inner nuclear layer and ganglion cell layer. Data between DSP and SMI showed high concordance with one another, identifying many genes in each layer. Citation Format: Charles Glaser, Su Ma, Wei Yang, Yan Liang, Joeseph Beechem, Vera L. Bonilha, Sujata Rao, William Horrigan, Bela Anand-Apte. Spatial transcriptomic profiling of the human and mouse retina prepared with CryoJane Tape Transfer System using GeoMx and CosMx spatial analysis. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 5646.

미세 입자 분리를 위한 유체 채널 내 폴리머 벽을 포함한 음파영동 디바이스의 제작

In this paper, we propose acoustophoretic microfluidic devices with an acoustic transparent polymer wall using a simple and low-cost fabrication method followed by MEMS (Micro-Electromechanical Systems) processes. Generally, due to the acoustic standing wave between two opposing walls in microfluidic channel, the particle focusing lines are fixed according to the applied frequency. In the proposed device, however, it is possible to place the particle focusing lines in the arbitrary position within the fluidic domain through the optimized width of polymer wall. The PDMS (Polydimethylsiloxane) mold with thin layer was used as the sealing layer between the Si substrate and cover glass, as well as the decoupling layer between the acoustic boundary and fluidic boundary. The thickness of PDMS mold needed to be minimized to decrease the heating by the acoustic energy absorption of PDMS layer, which was successfully made using the spin-coating of PDMS and the UV tape transfer method. The acoustophoretic device with thin PDMS layer and optimized width of PDMS wall can be applied, for biotechnological applications such as the separation of blood cells and micro-particles.

Rapid prototyping of heterostructured organic microelectronics using wax printing, filtration, and transfer.

Conducting polymers are the natural choice for soft electronics. However, the main challenge is to pattern conducting polymers using a simple and rapid method to manufacture advanced devices. Filtration of conducting particle dispersions using a patterned membrane is a promising method. Here, we show the rapid prototyping of various micropatterned organic electronic heterostructures of PEDOT:PSS by inducing the formation of microscopic hydrogels, which are then filtered through membranes containing printed hydrophobic wax micropatterns. The hydrogels are retained on the un-patterned, hydrophilic regions, forming micropatterns, achieving a resolution reaching 100 μm. We further solve the problem of forming stacked devices by transferring the acidified PEDOT:PSS micropattern using the adhesive tape transfer method to form vertical heterostructures with other micropatterned electronic colloids such as CNTs, which are patterned using a similar technique. We demonstrate a number of different heterostructure devices including micro supercapacitors and organic electrochemical transistors and also demonstrate the use of acidified PEDOT:PSS microstructures in cell cultures to enable bioelectronics.

Plasmonic-tape-attached multilayered MoS2 film for near-infrared photodetection

Molybdenum disulfide has been intensively studied as a promising material for photodetector applications because of its excellent electrical and optical properties. We report a multilayer MoS2 film attached with a plasmonic tape for near-infrared (NIR) detection. MoS2 flakes are chemically exfoliated and transferred onto a polymer substrate, and silver nanoparticles (AgNPs) dewetted thermally on a substrate are transferred onto a Scotch tape. The Scotch tape with AgNPs is attached directly and simply onto the MoS2 flakes. Consequently, the NIR photoresponse of the MoS2 device is critically enhanced. The proposed tape transfer method enables the formation of plasmonic structures on arbitrary substrates, such as a polymer substrate, without requiring a high-temperature process. The performance of AgNPs-MoS2 photodetectors is approximately four times higher than that of bare MoS2 devices.

A modified tape transfer approach for rapidly preparing high-quality cryosections of undecalcified adult rodent bones.

Background/ObjectiveHistology-based analyses are important tools to dissect cellular and molecular mechanisms of skeletal homeostasis, diseases, and regeneration. The success of these efforts is highly dependent on rapidly obtaining high-quality sections of mineralized skeletal tissues suitable for various analyses. However, the current techniques for preparing such sections are still far from satisfactory. This study aimed to develop a new approach for preparing high-quality undecalcified bone sections applicable to various histological analyses.MethodsTwo important modifications were made to the conventional Cryojane Tape-Transfer System, including utilization of an optimized adhesive to prepare adhesive glass slides for improving the transfer efficiency, and a cheap conventional benchtop UV transilluminator for UV curing. Cryosections of undecalcified rodent bones were prepared using this modified tape transfer approach, and their tissue morphology and structural integrity were visually examined. A variety of histological analyses, including calcein labeling, Von kossa staining, immunofluorescence, and enzymatic activity staining as well as 5-Ethynyl-2’-deoxyuridine (EdU) and TUNEL assays, were performed on these sections.ResultsWe developed a modified version of tape transfer approach that can prepare cryosections of undecalcified rodent adult bones within 4 days at a low cost. Bone sections prepared by this approach exhibited good tissue morphology and structural integrity. Moreover, these sections were applicable to a variety of histological analyses, including calcein labeling, Von kossa staining, immunofluorescence, and enzymatic activity staining as well as EdU and TUNEL assays.ConclusionThe tape transfer approach we developed provides a rapid, affordable, and easy learning method for preparing high-quality undecalcified bone sections valuable for bone research.The translational potential of this articleOur research provides a rapid, affordable, and easy learning method for preparing high-quality undecalcified bone sections that can be potentially used for accurate diagnosis of various bone disorders and evaluation of the efficacy of different therapies in the treatment of these diseases.

High-performance Acetone Soluble Tape Transfer Printing Method for Heterogeneous Integration

A high-performance transfer printing method using a new soluble tape which can be dissolved in acetone is proposed to be used in heterogeneous integration. Si inks array was transferred from SOI wafers onto various substrates without adhesion promoter by this new method which we refer to as the acetone soluble tape (AST) method to compare with other transfer printing methods by using thermal release tape (TRT), water soluble tape (WST) and polydimethylsiloxane (PDMS). By using the AST method, the transfer printing process does not involve interface contention between stamp/inks and inks/receiver substrate so that it maximizes the transfer printing efficiency. Experimental results present the AST method has good performances, and various alien substrates, even curvilinear surfaces, can be selected as receiver substrates by the AST method. To examine the quality of the transferred Si inks, the Si TFTs were fabricated by using the Si membrane transferred by the AST method on sapphire substrate and the devices show the good performance. All the results confirm that the AST method is an effective method in heterogeneous integration.

A high-throughput neurohistological pipeline for brain-wide mesoscale connectivity mapping of the common marmoset.

Understanding the connectivity architecture of entire vertebrate brains is a fundamental but difficult task. Here we present an integrated neuro-histological pipeline as well as a grid-based tracer injection strategy for systematic mesoscale connectivity mapping in the common marmoset (Callithrix jacchus). Individual brains are sectioned into ~1700 20 µm sections using the tape transfer technique, permitting high quality 3D reconstruction of a series of histochemical stains (Nissl, myelin) interleaved with tracer labeled sections. Systematic in-vivo MRI of the individual animals facilitates injection placement into reference-atlas defined anatomical compartments. Further, by combining the resulting 3D volumes, containing informative cytoarchitectonic markers, with in-vivo and ex-vivo MRI, and using an integrated computational pipeline, we are able to accurately map individual brains into a common reference atlas despite the significant individual variation. This approach will facilitate the systematic assembly of a mesoscale connectivity matrix together with unprecedented 3D reconstructions of brain-wide projection patterns in a primate brain.

Large-energy passively Q-switched Er-doped fiber laser based on CVD-Bi2Se3 as saturable absorber

In our work, Bi2Se3 was successfully used for demonstrating a large-energy passively Q-switched erbium-doped fiber laser. Bi2Se3 nanosheets were fabricated by a catalyst-free chemical vapor deposition method. Based on a pyrolysis tape transfer method, the Bi2Se3 thin film on the SiO2 substrate was transferred to the end of the optical connector for constructing the fiber-integrated saturable absorber. The saturation intensity and modulation depth of the Bi2Se3 saturable absorber were 81.1 MW/cm2 and 15.7%, respectively. A stable Q-switched operation at 1549.99 nm with a maximum average output power of 23.61 mW was achieved. The minimum pulse duration and the largest pulse energy were 1.34 μs and 224.5 nJ, respectively. In comparison with previous works, the single pulse energy (224.5 nJ) obtained in our experiment was improved significantly. Our experimental results fully proved that CVD-Bi2Se3 has good performance in obtaining large energy pulse operations and will promote the applications of 2D CVD-materials in the field of pulse laser.

Tape nanolithography: a rapid and simple method for fabricating flexible, wearable nanophotonic devices

This paper describes a tape nanolithography method for the rapid and economical manufacturing of flexible, wearable nanophotonic devices. This method involves the soft lithography of a donor substrate with air-void nanopatterns, subsequent deposition of materials onto the substrate surface, followed by direct taping and peeling of the deposited materials by an adhesive tape. Without using any sophisticated techniques, the nanopatterns, which are preformed on the surface of the donor substrate, automatically emerge in the deposited materials. The nanopatterns can then be transferred to the tape surface. By leveraging the works of adhesion at the interfaces of the donor substrate-deposited material-tape assembly, this method not only demonstrates sub-hundred-nanometer resolution in the transferred nanopatterns on an area of multiple square inches but also exhibits high versatility and flexibility for configuring the shapes, dimensions, and material compositions of tape-supported nanopatterns to tune their optical properties. After the tape transfer, the materials that remain at the bottom of the air-void nanopatterns on the donor substrate exhibit shapes complementary to the transferred nanopatterns on the tape surface but maintain the same composition, thus also acting as functional nanophotonic structures. Using tape nanolithography, we demonstrate several tape-supported plasmonic, dielectric, and metallo-dielectric nanostructures, as well as several devices such as refractive index sensors, conformable plasmonic surfaces, and Fabry-Perot cavity resonators. Further, we demonstrate tape nanolithography-assisted manufacturing of a standalone plasmonic nanohole film and its transfer to unconventional substrates such as a cleaved facet and the curved side of an optical fiber.

Recent advances on mechanics of transfer printing for flexible and stretchable electronics

Flexible and stretchable inorganic electronics, offering the high performance of conventional electronics with the ability to be deformed like a rubber, integrate inorganic electronic materials with flexible substrates and has enabled many novel applications ranging from curvilinear electronics, epidermal electronics to bio-integrated electronics. However, inorganic electronic materials (e.g., silicon) cannot be fabricated directly on a flexible substrate due to the extreme processing conditions (e.g., high temperature). To overcome this challenge, transfer printing techniques have been developed to pick up inorganic thin films from the grown substrate and transfer them onto the receiver substrate for the heterogeneous integration. This approach separates the fabrication substrate with the application substrate and provides a most promising solution for the integration of inorganic electronic materials with flexible substrates to develop flexible and stretchable electronics. This paper provides a brief review of recent advances on mechanics of transfer printing techniques for flexible and stretchable inorganic electronics including kinetically controlled transfer printing technique, shear-enhanced transfer printing technique, gecko inspired transfer printing technique, surface-relief-assisted transfer printing technique, laser-driven transfer printing technique, bending curvature controlled transfer printing technique and tape transfer printing technique. The basic concepts for each transfer printing technique are overviewed to illustrate the key roles of mechanics in the development of transfer printing techniques. Despite the successful developments of various transfer printing techniques, several challenges still exist for future transfer printing techniques with the capabilities of transfer printing of nano-devices and direct three-dimensional transfer printing in a large-scale and high-efficiency manner.

THEORETICAL AND EXPERIMENTAL STUDY OF TAPE TRANSFER PRINTING FOR STRETCHABLE ELECTRONIC FABRICATION

Transfer printing is an effective way to assemble a soft stamp to transfer solid components from one substrate to a soft target substrate. The critical parameter in transfer printing is the adhesion force at the electronic devices/silicon interface. This paper proposes an improved transfer printing method based on polyvinyl alcohol (PVA) water-soluble tape for reducing the interfacial energy at stretchable electronics/glass interface. Whether the stretchable electronics are peeled off successfully or not, depends on the peeling energy release rate, which is obtained by the home-made peeling experiment platform for stretchable electronics delaminated from the rigid glass. Compared with polydimethylsiloxane (PDMS) substrate, the critical energy release rate is reduced by 60% via PVA tape transfer printing which is helpful to delaminate the stretchable electronics from the glass surface. The improved transfer printing method provides an effective way for the stretchable electronics to be directly printed to the soft target tissues.

Cryo-Imaging and Software Platform for Analysis of Molecular MR Imaging of Micrometastases.

We created and evaluated a preclinical, multimodality imaging, and software platform to assess molecular imaging of small metastases. This included experimental methods (e.g., GFP-labeled tumor and high resolution multispectral cryo-imaging), nonrigid image registration, and interactive visualization of imaging agent targeting. We describe technological details earlier applied to GFP-labeled metastatic tumor targeting by molecular MR (CREKA-Gd) and red fluorescent (CREKA-Cy5) imaging agents. Optimized nonrigid cryo-MRI registration enabled nonambiguous association of MR signals to GFP tumors. Interactive visualization of out-of-RAM volumetric image data allowed one to zoom to a GFP-labeled micrometastasis, determine its anatomical location from color cryo-images, and establish the presence/absence of targeted CREKA-Gd and CREKA-Cy5. In a mouse with >160 GFP-labeled tumors, we determined that in the MR images every tumor in the lung >0.3 mm2 had visible signal and that some metastases as small as 0.1 mm2 were also visible. More tumors were visible in CREKA-Cy5 than in CREKA-Gd MRI. Tape transfer method and nonrigid registration allowed accurate (<11 μm error) registration of whole mouse histology to corresponding cryo-images. Histology showed inflammation and necrotic regions not labeled by imaging agents. This mouse-to-cells multiscale and multimodality platform should uniquely enable more informative and accurate studies of metastatic cancer imaging and therapy.

Thermal Release Transfer Printing for Stretchable Conformal Bioelectronics.

Soft neural electrode arrays that are mechanically matched between neural tissues and electrodes offer valuable opportunities for the development of disease diagnose and brain computer interface systems. Here, a thermal release transfer printing method for fabrication of stretchable bioelectronics, such as soft neural electrode arrays, is presented. Due to the large, switchable and irreversible change in adhesion strength of thermal release tape, a low‐cost, easy‐to‐operate, and temperature‐controlled transfer printing process can be achieved. The mechanism of this method is analyzed by experiments and fracture‐mechanics models. Using the thermal release transfer printing method, a stretchable neural electrode array is fabricated by a sacrificial‐layer‐free process. The ability of the as‐fabricated electrode array to conform different curvilinear surfaces is confirmed by experimental and theoretical studies. High‐quality electrocorticography signals of anesthetized rat are collected with the as‐fabricated electrode array, which proves good conformal interface between the electrodes and dura mater. The application of the as‐fabricated electrode array on detecting the steady‐state visual evoked potentials research is also demonstrated by in vivo experiments and the results are compared with those detected by stainless‐steel screw electrodes.

High Fidelity Tape Transfer Printing Based On Chemically Induced Adhesive Strength Modulation.

Transfer printing, a two-step process (i.e. picking up and printing) for heterogeneous integration, has been widely exploited for the fabrication of functional electronics system. To ensure a reliable process, strong adhesion for picking up and weak or no adhesion for printing are required. However, it is challenging to meet the requirements of switchable stamp adhesion. Here we introduce a simple, high fidelity process, namely tape transfer printing(TTP), enabled by chemically induced dramatic modulation in tape adhesive strength. We describe the working mechanism of the adhesion modulation that governs this process and demonstrate the method by high fidelity tape transfer printing several types of materials and devices, including Si pellets arrays, photodetector arrays, and electromyography (EMG) sensors, from their preparation substrates to various alien substrates. High fidelity tape transfer printing of components onto curvilinear surfaces is also illustrated.

Tape transfer atomization patterning of liquid alloys for microfluidic stretchable wireless power transfer.

Stretchable electronics offers unsurpassed mechanical compliance on complex or soft surfaces like the human skin and organs. To fully exploit this great advantage, an autonomous system with a self-powered energy source has been sought for. Here, we present a new technology to pattern liquid alloys on soft substrates, targeting at fabrication of a hybrid-integrated power source in microfluidic stretchable electronics. By atomized spraying of a liquid alloy onto a soft surface with a tape transferred adhesive mask, a universal fabrication process is provided for high quality patterns of liquid conductors in a meter scale. With the developed multilayer fabrication technique, a microfluidic stretchable wireless power transfer device with an integrated LED was demonstrated, which could survive cycling between 0% and 25% strain over 1,000 times.

Tape transfer printing of a liquid metal alloy for stretchable RF electronics.

In order to make conductors with large cross sections for low impedance radio frequency (RF) electronics, while still retaining high stretchability, liquid-alloy-based microfluidic stretchable electronics offers stretchable electronic systems the unique opportunity to combine various sensors on our bodies or organs with high-quality wireless communication with the external world (devices/systems), without sacrificing enhanced user comfort. This microfluidic approach, based on printed circuit board technology, allows large area processing of large cross section conductors and robust contacts, which can handle a lot of stretching between the embedded rigid active components and the surrounding system. Although it provides such benefits, further development is needed to realize its potential as a high throughput, cost-effective process technology. In this paper, tape transfer printing is proposed to supply a rapid prototyping batch process at low cost, albeit at a low resolution of 150 μm. In particular, isolated patterns can be obtained in a simple one-step process. Finally, a stretchable radio frequency identification (RFID) tag is demonstrated. The measured results show the robustness of the hybrid integrated system when the tag is stretched at 50% for 3000 cycles.

Increased Value of Video Assets: New Technologies for the Automatic Transfer and Digital Preservation of Analog Videocassettes

Millions of videocassettes are still stored on shelves, carrying valuable content waiting to be transferred into files before decomposing. Time is running short: not only does tape stock decay, but videotape recorder (VTR) availability becomes critical, and VTR service experts are becoming rare. As it is the final transfer, a technology for highly automated large-scale and lossless transfer that recovers and retains the original signal on tape is required. Direct tape transfer is a new technology that directly converts the off-tape signal from analog videotapes into digital files without passing through conventional playback circuits and its quality-degrading multiple analog-to-digital and digital-to-analog conversions of standard video playback equipment. By digitizing the radio frequency (RF) tape signal directly, all subsequent signal processes can be done by software with a much higher resolution than any that conventional VTR allows. Intelligent signal regeneration by smart dropout prevention and digital concealment algorithms allows signal recovery far beyond the possibilities of traditional dropout compensation circuitry. The paper explains the technical details of direct tape transfer technology, which was developed in a joint research project by the Fraunhofer Institute for Integrated Circuits IIS and Cube-Tec International GmbH.

Computer-Automated Static, Dynamic and Cellular Bone Histomorphometry.

Dynamic and cellular histomorphometry of trabeculae is the most biologically relevant way of assessing steady state bone health. Traditional measurement involves manual visual feature identification by a trained and qualified professional. Inherent with this methodology is the time and cost expenditure, as well as the subjectivity that naturally arises under human visual inspection. In this work, we propose a rapidly deployable, automated, and objective method for dynamic histomorphometry. We demonstrate that our method is highly effective in assessing cellular activities in distal femur and vertebra of mice which are injected with calcein and alizarin complexone 7 and 2 days prior to sacrifice. The mineralized bone tissues of mice are cryosectioned using a tape transfer protocol. A sequential workflow is implemented in which endogenous fluorescent signals (bone mineral, green and red mineralization lines), tartrate resistant acid phosphatase identified by ELF-97 and alkaline phosphatase identified by Fast Red are captured as individual tiled images of the section for each fluorescent color. All the images are then submitted to an image analysis pipeline that automates identification of the mineralized regions of bone and selection of a region of interest. The TRAP and AP stained images are aligned to the mineralized image using strategically placed fluorescent registration beads. Fluorescent signals are identified and are related to the trabecular surface within the ROI. Subsequently, the pipelined method computes static measurements, dynamic measurements, and cellular activities of osteoclast and osteoblast related to the trabecular surface. Our method has been applied to the distal femurs and vertebrae of 8 and 16 week old male and female C57Bl/6J mice. The histomorphometric results reveal a significantly greater bone turnover rate in female in contrast to male irrespective of age, validating similar outcomes reported by other studies.

Muscular Anatomy of the Human Ventricular Folds

Our purpose in this study was to better understand the muscular anatomy of the ventricular folds in order to help improve biomechanical modeling of phonation and to better understand the role of these muscles during phonatory and nonphonatory tasks. Four human larynges were decalcified, sectioned coronally from posterior to anterior by a CryoJane tape transfer system, and stained with Masson's trichrome. The total and relative areas of muscles observed in each section were calculated and used for characterizing the muscle distribution within the ventricular folds. The ventricular folds contained anteriorly coursing thyroarytenoid and ventricularis muscle fibers that were in the lower half of the ventricular fold posteriorly, and some ventricularis muscle was evident in the upper and lateral portions of the fold more anteriorly. Very little muscle tissue was observed in the medial half of the fold, and the anterior half of the ventricular fold was largely devoid of any muscle tissue. All 4 larynges contained muscle bundles that coursed superiorly and medially through the upper half of the fold, toward the lateral margin of the epiglottis. Although variability of expression was evident, a well-defined thyroarytenoid muscle was readily apparent lateral to the arytenoid cartilage in all specimens.