The work on eye research in this laboratory is supported by American Health Assistant Foundation, Azalea (1972) Endowment Fund, and HKU Small Project Fund (20097176185).

1. Tools 
Microscope, Nikon
Stereo Investigator, MBF Bioscience &#x2013; MicroBrightField, Inc.
2. Preparation
<ol>
 <li>Before working on any morphometric analysis, each retina sample is sectioned at 4 micron thickness and undergoes the H&amp;E staining.</li>
 <li>The retina section is divided into 4 regions &#x2013; upper peripheral region, the upper central region, the lower peripheral region, and the lower central region.</li>
 <li>After defining the regions, an image of each region is acquired at 10x40 magnifications under the bright beam microscope of Nikon.</li>
 <li>Now, we are ready to analyze morphometry of the retina.</li>
</ol>
3. Measuring INL thickness
<ol>
 <li>Four measurements of INL thickness in each region were measured. Four lines will be drawn perpendicularly from the contour baseline to the outer border of the INL.</li>
 <li>Open the software called Stereo Investigator and choose the 40x Lens from the Main Toolbar.</li>
 <li>Select "Image Open" under the tab "File". Choose an image of a desired retinal region that you would like to analyze.</li>
 <li>Choose the type of contour line from the Dropdown list box of the Main Toolbar and press the &#x201C;Auto Move&#x201D; button.</li>
 <li>Right click in the tracing window, and select "Simple Click Tracing".</li>
 <li>Draw the contour line along the inner border of the INL.</li>
 <li>When the drawing is done, right click in the tracing window and choose "End Open Contour".</li>
 <li>Select a marker at the marker toolbar and add markers at the junction points.</li>
 <li>After adding all the markers, deselect the marker icon at the Marker Toolbar.</li>
 <li>Position a cursor at the centre of one of the markers.</li>
 </ol>
 <img src="/files/ftp_upload/3377/3377fig1.jpg" alt="Figure 1" />
 <ol start="11">
 <li>Select "Quick Measure Angle" under the tab "Tools".</li>
 </ol>
 <img src="/files/ftp_upload/3377/3377fig2.jpg" alt="Figure 2" />
 <ol start="12">
 <li>Right click in the tracing window and deselect the "Continuous" option. </li>
 <li>Measure an angle by first clicking at the center of a marker, which is adjacent to the marker selected for an end of the line segment.</li>
 </ol>
 <img src="/files/ftp_upload/3377/3377fig3.jpg" alt="Figure 3" />
 <ol start="14">
 <li>Then, move the mouse to the center of the concerned marker and click again.</li>
 <li> Extend the rubber band line to the outer border of the INL. </li>
 <li>Adjust the angle until 90&deg; is reached.</li>
 </ol>
 <img src="/files/ftp_upload/3377/3377fig4.jpg" alt="Figure 4" />
 <ol start="17">
 <li>Left click at the desired position. A dialog box showing an angle measurement will pop up right after the click. </li>
 <li>Press the "Enter" key while holding the mouse still.</li>
 </ol>
 <img src="/files/ftp_upload/3377/3377fig5.jpg" alt="Figure 5" />
 <ol start="19">
 <li> Left click the tracing window so that a line is drawn from one end to the new selected end.</li>
 <li> Right click in the tracing window and choose "End Open Contour". </li>
 </ol>
 <img src="/files/ftp_upload/3377/3377fig6.jpg" alt="Figure 6" />
 <ol start="21">
 <li> Draw the other lines at different positions in exactly the same way as described before. </li>
 <li>After drawing all the lines, select the Editing mode and rename the 4 line segments accordingly. </li>
 <li> Four measurements can be obtained by pressing "Contour Measurement" button. </li>
 <li>Select these 4 measurements and paste them to a spreadsheet by clicking "Copy to Clipboard". </li>
 <li>Select "Save As" under the tab "File". The tracing data can be saved as a data file. </li>
</ol>
4. Quantifying the number of RGCs
<ol>
 <li>Select "Image Open" under the tab "File". Choose an image of a desired retinal region that you would like to analyze. </li>
 <li>Choose the type of contour line from the Dropdown list box of the Main Toolbar. </li>
 <li> Draw a contour line along the border of nerve fiber layer (NFL). </li>
 <li>End the tracing with the option "End Open Contour". </li>
 <li>At each end, add one marker at the tip of the line and another at the position near the tip. </li>
 <li>Deselect the marker icon at the marker toolbar. </li>
 <li>Position a cursor at the centre of the markers at the tip. </li>
 <li>Select "Quick Measure Angle" under the tab &#x201C;Tools". </li>
 <li>Right click in the tracing window and deselect the "Continuous" option. </li>
 <li>Adjust the rubber band lines and measure an angle of 90&deg;. </li>
 <li>Press the "Enter" key after a dialog box is popped up. </li>
 <li>Left click the tracing window so that a new line can be perpendicularly extended from the tip. </li>
 <li>Draw another new line in the exactly the same way at another end. </li>
 <li>Two boundaries are created within which the number of RGCs is counted. </li>
 <li>Choose one boundary as an exclusion line which the cell touches is not counted. </li>
 <li>Select one type of marker and attach one to each live cell. </li>
 <li>Select another type of marker for the dead cells. </li>
 <li> The number of each type of markers placed will be displayed alongside the marker icon accordingly at the marker toolbar. </li>
 <li> Select the Editing mode and pick up the contour baseline. Right click in the tracing window and rename the line. </li>
 <li> The length of the contour baseline can be obtained by pressing "Contour Measurement" button. </li>
 <li> The number of the cells can then be expressed per mm of the length. </li>
 <li> Select "Save As" under the tab "File". The tracing and the marker data can be saved as a data file. </li>
</ol>
 5. Measuring the cell size of a RGC cell
<ol>
 <li>Select "Image Open" under the tab "File". Choose an image of a desired retinal region that you would like to analyze. </li>
 <li>Zoom in a live cell and choose the type of contour line from the Dropdown list box of the Main Toolbar. </li>
 <li>Draw a contour line along the circumference of the cell. </li>
 <li>At about the end, right click the tracing window and select "End close contour". </li>
 <li>The area of the cell will be displayed under the item of Area in the Contour Measurement dialog box. </li>
</ol>

<ol>
	<li>Lam, T. T., Abler, A. S., Tso, M. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=N-Methyl-D-Aspartate+(NMDA)â&#x20AC;&#x201C;Induced+Apoptosis+in+Rat+Retina.">N-Methyl-D-Aspartate (NMDA)â&#x20AC;&#x201C;Induced Apoptosis in Rat Retina.</a> Investigative Ophthalmology &amp; Visual Science. 40, 2391-2397 (1999).</li><li>Lam, T. T., Abler, A. S., Tso, M. O. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Apoptosis+and+caspases+after+ischemia-reperfusion+injury+in+rat+retina.">Apoptosis and caspases after ischemia-reperfusion injury in rat retina.</a> Invest. Ophthalmol. Vis. Sci. 40, 967-975 (1999).</li><li>Luo, X. G., Chiu, K., Lau, H. S., Lee, V. W. H., Yung, K. K. L., So, K. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+Selective+Vulnerability+of+Retinal+Ganglion+Cells+in+Rat+Chronic+Ocular+Hypertension+Model+at+Early+Phase.">The Selective Vulnerability of Retinal Ganglion Cells in Rat Chronic Ocular Hypertension Model at Early Phase.</a> Cellular and Molecular Neurobiology. 29 (8), 1143-1151 (2009).</li><li>Han, Y. S., Chung, I. Y., Park, J. M., Yu, J. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuroprotective+effect+of+citicoline+on+retinal+cell+damage+induced+by+kainic+acid+in+rats.">Neuroprotective effect of citicoline on retinal cell damage induced by kainic acid in rats.</a> Korean J. Ophthalmol. 19, 219-226 (2005).</li><li>Hernandez, M., Urcola, J. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Retinal+ganglion+cell+neuroprotection+in+a+rat+model+of+glaucoma+following+brimonidine,+latanoprost+or+combined+treatments.">Retinal ganglion cell neuroprotection in a rat model of glaucoma following brimonidine, latanoprost or combined treatments.</a> Exp. Eye Res. 86, 798-806 (2008).</li><li>Chan, H. C., Chang, R. C. C., Ip, A. K. C., Chiu, K., Yuen, W. H., Zee, S. Y., So, K. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuroprotective+effects+of+Lycium+barbarum+Lynn+on+protecting+retinal+ganglion+cells+in+an+ocular+hypertension+model+of+glaucoma.">Neuroprotective effects of Lycium barbarum Lynn on protecting retinal ganglion cells in an ocular hypertension model of glaucoma.</a> Experimental Neurology. 203, 269-273 (2007).</li></ol>

The authors have nothing to disclose.

1. How to obtain a more accurate thickness measurement?
You can enlarge the image by clicking "Zoom in" button and left click in the tracing window. The INL border can be seen clearly. If the tip of the line is not at the outer border of the INL, we can adjust the line under the Editing mode. After picking the concerned line, right click the tracing window and choose "Insert Point in Selected Contour". A point can be added at the outer border while the point added should be along the same line. ...

A correction was made to <a href="http://www.jove.com/video/3377">Morphometric Analyses of Retinal Sections</a>. There was an error with an author's name.

Erratum: Morphometric Analyses of Retinal Sections

<table border="1">
	<tbody>
		<tr>
			<td>Name of the reagent</td>
			<td>Type</td>
			<td>Company</td>
			<td>Catalogue number</td>
		</tr>
		<tr>
			<td>Stereo Investigator</td>
			<td>MBF Bioscience Analysis Software</td>
			<td>MicroBright Field</td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td>Microscope</td>
			<td>Olympus BX51</td>
			<td>Olympus Corporation</td>
			<td>BX51</td>
		</tr>
	</tbody>
</table>

morphometric analyses of retinal sections

Morphometric analyses of retinal sections have been used in examining retinal diseases. For examples, neuronal cells were significantly lost in the retinal ganglion cell layer (RGCL) in rat models with N-methyl-D-aspartate (NMDA)&#x2013;induced excitotoxicity1, retinal ischemia-reperfusion injury2 and glaucoma3. Reduction of INL and inner plexiform layer (IPL) thicknesses were reversed with citicoline treatment in rats' eyes subjected to kainic acid-mediated glutamate excitotoxicity4. Alteration of RGC density and soma sizes were observed with different drug treatments in eyes with elevated intraocular pressure3,5,6. Therefore, having objective methods of analyzing the retinal morphometries may be of great significance in evaluating retinal pathologies and the effectiveness of therapeutic strategies.
The retinal structure is multi-layers and several different kinds of neurons exist in the retina. The morphometric parameters of retina such as cell number, cell size and thickness of different layers are more complex than the cell culture system. Early on, these parameters can be detected using other commercial imaging software. The values are normally of relative value, and changing to the precise value may need further accurate calculation. Also, the tracing of the cell size and morphology may not be accurate and sensitive enough for statistic analysis, especially in the chronic glaucoma model. The measurements used in this protocol provided a more precise and easy way. And the absolute length of the line and size of the cell can be reported directly and easy to be copied to other files. For example, we traced the margin of the inner and outer most nuclei in the INL and formed a line then using the software to draw a 90 degree angle to measure the thickness. While without the help of the software, the line maybe oblique and the changing of retinal thickness may not be repeatable among individual observers. In addition, the number and density of RGCs can also be quantified. This protocol successfully decreases the variability in quantitating features of the retina, increases the sensitivity in detecting minimal changes.
 	This video will demonstrate three types of morphometric analyses of the retinal sections. They include measuring the INL thickness, quantifying the number of RGCs and measuring the sizes of RGCs in absolute value. These three analyses are carried out with Stereo Investigator (MBF Bioscience &mdash; MicroBrightField, Inc.). The technique can offer a simple but scientific platform for morphometric analyses.

Watch this Scientific Journal Video about Morphometric Analyses of Retinal Sections at JoVE.com

Morphometric Analyses of Retinal Sections

This video demonstrates three types of morphometric analyses of the retina, which include measuring the inner nuclear layer thickness, quantifying the number of retinal ganglion cells (RGCs) and measuring the sizes of RGCs. The technique can offer a simple but scientific platform for morphometric analyses.

Morphometric analyses of retinal sections have been used in examining retinal diseases. For examples, neuronal cells were significantly lost in the ...

morphometric-analyses-of-retinal-sections

Research

JoVE Journal

Neuroscience

10.2K Views.  The University of Hong Kong. This video demonstrates three types of morphometric analyses of the retina, which include measuring the inner nuclear layer thickness, quantifying the number of retinal ganglion cells (RGCs) and measuring the sizes of RGCs. The technique can offer a simple but scientific platform for morphometric analyses.

Video: Morphometric Analyses of Retinal Sections

An Isolated Retinal Preparation to Record Light Response from Genetically Labeled Retinal Ganglion Cells

The first steps in vertebrate vision take place when light stimulates the rod and cone photoreceptors of the retina 1. This information is then segregated into what are known as the ON and OFF pathways. The photoreceptors signal light information to the bipolar cells (BCs), which depolarize in response to increases (On BCs) or decreases (Off BCs) in light intensity. This segregation of light information is maintained at the level of the retinal ganglion cells (RGCs), which have dendrites stratifying in either the Off sublamina of the inner plexiform layer (IPL), where they receive direct excitatory input from Off BCs, or stratifying in the On sublamina of the IPL, where they receive direct excitatory input from On BCs. This segregation of information regarding increases or decreases in illumination (the On and Off pathways) is conserved and signaled to the brain in parallel.
The RGCs are the output cells of the retina, and are thus an important cell to study in order to understand how light information is signaled to visual nuclei in the brain. Advances in mouse genetics over recent decades have resulted in a variety of fluorescent reporter mouse lines where specific RGC populations are labeled with a fluorescent protein to allow for identification of RGC subtypes 2 3 4 and specific targeting for electrophysiological recording. Here, we present a method for recording light responses from fluorescently labeled ganglion cells in an intact, isolated retinal preparation. This isolated retinal preparation allows for recordings from RGCs where the dendritic arbor is intact and the inputs across the entire RGC dendritic arbor are preserved. This method is applicable across a variety of ganglion cell subtypes and is amenable to a wide variety of single-cell physiological techniques.

This article provides a description of how to dissect and record from the isolated retinal preparation in mouse. In particular, we describe how to record light responses from a fluorescently labeled ganglion cell population and subsequently identify and analyze its morphology.

The first steps in vertebrate vision take place when light stimulates the rod and cone photoreceptors of the retina 1.  This information is then ...

Protocol for Three-dimensional Confocal Morphometric Analysis of Astrocytes

As glial cells in the brain, astrocytes have diverse functional roles in the central nervous system. In the presence of harmful stimuli, astrocytes modify their functional and structural properties, a condition called reactive astrogliosis. Here, a protocol for assessment of the morphological properties of astrocytes is presented. This protocol includes quantification of 12 different parameters i.e. the surface area and volume of the tissue covered by an astrocyte (astrocyte territory), the entire astrocyte including branches, cell body, and nucleus, as well as total length and number of branches, the intensity of fluorescence immunoreactivity of antibodies used for astrocyte detection, and astrocyte density (number/1,000 &#181;m2). For this purpose three-dimensional (3D) confocal microscopic images were created, and 3D image analysis software such as Volocity 6.3 was used for measurements. Rat brain tissue exposed to amyloid beta1-40 (A&#946;1-40) with or without a therapeutic&#160;intervention was used to present the method. This protocol can also be used for 3D morphometric analysis of other cells from either in vivo or in vitro conditions.

Astrocytes in the CNS change their functional and structural properties in response to harmful stimuli. This report presents a protocol for assessment of three-dimensional astrocyte morphology in diseased conditions or after therapeutic interventions.

As glial cells in the brain, astrocytes have diverse functional roles in the central nervous system. In the presence of harmful stimuli, astrocytes modify ...

Immunostaining of Biocytin-filled and Processed Sections for Neurochemical Markers

Electrophysiological recordings of cells using the patch clamp technique have allowed for the identification of different neuronal types based on firing patterns. The inclusion of biocytin/neurobiotin in the recording electrode permits post-hoc recovery of morphological details, which are necessary to determine the dendritic arborization and the regions targeted by the axons of the recorded neurons. However, given the presence of morphologically similar neurons with distinct neurochemical identities and functions, immunohistochemical staining for cell-type-specific proteins is essential to definitively identify neurons. To maintain network connectivity, brain sections for physiological recordings are prepared at a thickness of 300 &#181;m or greater. However, this thickness often hinders immunohistological postprocessing due to issues with antibody penetration, necessitating the resectioning of the tissue. Resectioning of slices is a challenging art, often resulting in the loss of tissue and morphology of the cells from which electrophysiological data was obtained, rendering the data unusable. Since recovery of morphology would limit data loss and guide in the selection of neuronal markers, we have adopted a strategy of recovering cell morphology first, followed by secondary immunostaining. We introduce a practical approach to biocytin filling during physiological recordings and subsequent serial immunostaining for the recovery of morphology, followed by the restaining of sections to determine the neurochemical identity. We report that sections that were filled with biocytin, fixed with paraformaldehyde (PFA), stained, and coverslipped can be removed and restained with a second primary antibody days later. This restaining involves the removal of the coverslip, the washing of sections in a buffer solution, and the incubation of primary and secondary antibodies to reveal the neurochemical identity. The method is advantageous for eliminating data loss due to an inability to recover morphology and for narrowing down the neurochemical markers to be tested based on morphology.

This protocol presents a method for the morphological recovery of neurons patched during electrophysiological recordings using biocytin filling and subsequent immunohistochemical postprocessing. We show that thick biocytin-filled sections that were stained and coverslipped can be restained with a second primary antibody days&#160;or months later.

Electrophysiological recordings of cells using the patch clamp technique have allowed for the identification of different neuronal types based on firing ...

Microstate and Omega Complexity Analyses of the Resting-state Electroencephalography

Microstate and omega complexity are two reference-free electroencephalography (EEG) measures that can represent the temporal and spatial complexities of EEG data and have been widely used to investigate the neural mechanisms in some brain disorders. The goal of this article is to describe the protocol underlying EEG microstate and omega complexity analyses step by step. The main advantage of these two measures is that they could eliminate the reference-dependent problem inherent to traditional spectrum analysis. In addition, microstate analysis makes good use of high time resolution of resting-state EEG, and the four obtained microstate classes could match the corresponding resting-state networks respectively. The omega complexity characterizes the spatial complexity of the whole brain or specific brain regions, which has obvious advantage compared with traditional complexity measures focusing on the signal complexity in a single channel. These two EEG measures could complement each other to investigate the brain complexity from the temporal and spatial domain respectively.

This article describes the protocol underlying electroencephalography (EEG) microstate analysis and omega complexity analysis, which are two reference-free EEG measures and highly valuable to explore the neural mechanisms of brain disorders.

Microstate and omega complexity are two reference-free electroencephalography (EEG) measures that can represent the temporal and spatial complexities of ...

Preparation of Mouse Retinal Cryo-sections for Immunohistochemistry

Preparation of high-quality mouse eye sections for immunohistochemistry (IHC) is critical for assessing the retinal structure and function and for determining the mechanisms underlying retinal diseases. Maintaining structural integrity throughout the tissue preparation is vital for obtaining reproducible retinal IHC data but can be challenging due to the fragility and complexity of retinal cytoarchitecture. Strong fixatives like 10% formalin or Bouin's solution optimally preserve the retinal structure, they often impede IHC analysis by enhancing the background fluorescence and/or diminishing antibody-epitope interactions, a process known as epitope masking. Milder fixatives, on the other hand, like 4% paraformaldehyde, reduces background fluorescence and epitope-masking, meticulous dissection techniques must be utilized to preserve the retinal structure. In this article, we present a comprehensive method to prepare mouse ocular posterior cups for IHC that is sufficient to preserve most antibody-epitope interactions without loss of retinal structural integrity. We include representative IHC with antibodies to various retinal cell type markers to illustrate tissue preservation and orientation under optimal and sub-optimal conditions. Our goal is to optimize IHC studies of the retina by providing a complete protocol from ocular posterior cup dissection to IHC.

This report describes comprehensive methods for preparing frozen mouse retina sections for immunohistochemistry (IHC). Methods described include dissection of the ocular posterior cup, paraformaldehyde fixation, embedding in Optimal Cutting Temperature (OCT) media and tissue orientation, sectioning and immunostaining.

Preparation of high-quality mouse eye sections for immunohistochemistry (IHC) is critical for assessing the retinal structure and function and for ...

Preparation of Newborn Rat Brain Tissue for Ultrastructural Morphometric Analysis of Synaptic Vesicle Distribution at Nerve Terminals

Our laboratory and many others have exploited the high resolving power of transmission electron microscopy to study the morphology and spatial organization of synaptic vesicles. In order to obtain high-quality electron micrographs that can yield the degree of morphological detail necessary for quantitative analysis of pre-synaptic vesicle distribution, optimal specimen preparation is critical. Chemical fixation is the first step in the process of specimen preparation, and of utmost importance to preserve fine ultrastructure. Vascular fixation with a glutaraldehyde-formaldehyde solution, followed by treatment of vibratome-sectioned specimens with osmium tetroxide, stabilizes the maximum number of molecules, especially proteins and lipids, and results in superior conservation of ultrastructure. Tissue is then processed with counterstaining, sequential dehydration and resin-embedding. En bloc staining with uranyl acetate (i.e., staining of vibratome-sectioned tissue before resin embedding) enhances endogenous contrast and stabilizes cell components against extraction during specimen processing. Contrast can be further increased by applying uranyl acetate as a post-stain on ultrathin sections. Double-staining of ultrathin sections with lead citrate after uranyl acetate treatment also improves image resolution, by intensifying electron-opacity of nucleic acid-containing structures through selective binding of lead to uranyl acetate. Transmission electron microscopy is a powerful tool for characterization of the morphological details of synaptic vesicles and quantification of their size and spatial organization in the terminal bouton. However, because it uses fixed tissue, transmission electron microscopy can only provide indirect information regarding living or evolving processes. Therefore, other techniques should be considered when the main objective is to study dynamic or functional aspects of synaptic vesicle trafficking and exocytosis.

We describe procedures for processing newborn rat brain tissue to obtain high-resolution electron micrographs for morphometric analysis of synaptic vesicle distribution at nerve terminals. The micrographs obtained with these methods can also be used to study the morphology of a number of other cellular components and their dimensional structural relationships.

Our laboratory and many others have exploited the high resolving power of transmission electron microscopy to study the morphology and spatial ...

Collection of Frozen Rodent Brain Regions for Downstream Analyses

As our understanding of neurobiology has progressed, molecular analyses are often performed on small brain areas such as the medial prefrontal cortex (mPFC) or nucleus accumbens. The challenge in this work is to dissect the correct area while preserving the microenvironment to be examined. In this paper, we describe a simple, low-cost method using resources readily available in most labs. This method preserves nucleic acid and proteins by keeping the tissue frozen throughout the process. Brains are cut into 0.5&#8211;1.0 mm sections using a brain matrix and arranged on a frozen glass plate. Landmarks within each section are compared to a reference, such as the Allen Mouse Brain Atlas, and regions are dissected using a cold scalpel or biopsy punch. Tissue is then stored at -80 &#176;C until use. Through this process rat and mouse mPFC, nucleus accumbens, dorsal and ventral hippocampus and other regions have been successfully analyzed using qRT-PCR and Western assays. This method is limited to brain regions that can be identified by clear landmarks.

This procedure describes the collection of discrete frozen brain regions to obtain high-quality protein and RNA using inexpensive and commonly available tools.

As our understanding of neurobiology has progressed, molecular analyses are often performed on small brain areas such as the medial prefrontal cortex ...

Preparation of the Rat Vocal Fold for Neuromuscular Analyses

The purpose of this tutorial is to describe the preparation of the rat vocal fold for histochemical neuromuscular study. This protocol outlines procedures for rat laryngeal dissection, flash-freezing, and cryosectioning of the vocal folds. This study describes how to cryosection vocal folds in both longitudinal and cross-sectional planes. A novelty of this protocol is the laryngeal tracking during cryosectioning that ensures accurate identification of the intrinsic laryngeal muscles and reduces the chance of tissue loss. Figures demonstrate the progressive cryosectioning in both planes. Twenty-nine rat hemi-larynges were cryosectioned and tracked from the emergence of the thyroid cartilage to the appearance of the first section that included the full vocal fold. The full vocal fold was visualized for all animals in both planes. There was high variability in the distance from the appearance of the thyroid cartilage to the appearance of the full vocal fold in both planes. Weight was not correlated to depth of laryngeal landmarks, suggesting individual variability and other factors related to tissue preparation may be responsible for the high variability in the appearance of landmarks during sectioning. This study details a methodology and presents morphological data for preparing the rat vocal fold for histochemical neuromuscular investigation. Due to high individual variability, laryngeal landmarks should be closely tracked during cryosectioning to prevent oversectioning tissue and tissue loss. The use of a consistent methodology, including adequate tissue preparation and awareness of landmarks within the rat larynx, will assist with consistent results across studies and aid new researchers interested in using the rat vocal fold as a model to investigate laryngeal neuromuscular mechanisms.

This protocol describes methods used to prepare rat vocal folds for histochemical neuromuscular study.

The purpose of this tutorial is to describe the preparation of the rat vocal fold for histochemical neuromuscular study. This protocol outlines procedures ...

Dissection of Single Skeletal Muscle Fibers for Immunofluorescent and Morphometric Analyses of Whole-Mount Neuromuscular Junctions

The neuromuscular junction (NMJ) is a specialized point of contact between the motor nerve and the skeletal muscle. This peripheral synapse exhibits high morphological and functional plasticity. In numerous nervous system disorders, NMJ is an early pathological target resulting in neurotransmission failure, weakness, atrophy, and even in muscle fiber death. Due to its relevance, the possibility to quantitatively assess certain aspects of the relationship between NMJ components can help to understand the processes associated with its assembly/disassembly. The first obstacle when working with muscles is to gain the technical expertise to quickly identify and dissect without damaging their fibers. The second challenge is to utilize high-quality detection methods to obtain NMJ images that can be used to perform quantitative analysis. This article presents a step-by-step protocol for dissecting extensor digitorum longus and soleus muscles from rats. It also explains the use of immunofluorescence to visualize pre and postsynaptic elements of whole-mount NMJs. Results obtained demonstrate that this technique can be used to establish the microscopic anatomy of the synapsis and identify subtle changes in the status of some of its components under physiological or pathological conditions.

The ability to accurately detect neuromuscular junction components is crucial in evaluating modifications in its architecture because of pathological or developmental processes. Here we present a complete description of a straightforward method to obtain high-quality images of whole-mount neuromuscular junctions that can be used to perform quantitative measurements.

The neuromuscular junction (NMJ) is a specialized point of contact between the motor nerve and the skeletal muscle. This peripheral synapse exhibits high ...

Quantification of Immunostained Caspase-9 in Retinal Tissue

The family of caspases is known to mediate many cellular pathways beyond cell death, including cell differentiation, axonal pathfinding, and proliferation. Since the identification of the family of cell death proteases, there has been a search for tools to identify and expand the function of specific family members in development, health, and disease states. However, many of the currently commercially available caspase tools that are widely used are not specific for the targeted caspase. In this report, we delineate the approach we have used to identify, validate, and target caspase-9 in the nervous system using a novel inhibitor and genetic approaches with immunohistochemical read-outs. Specifically, we used the retinal neuronal tissue as a model to identify and validate the presence and function of caspases. This approach enables the interrogation of cell-type specific apoptotic and non-apoptotic caspase-9 functions and can be applied to other complex tissues and caspases of interest. Understanding the functions of caspases can help to expand current knowledge in cell biology, and can also be advantageous to identify potential therapeutic targets due to their involvement in disease.

Presented here is a detailed immunohistochemistry protocol to identify, validate, and target functionally relevant caspases in complex tissues.