We would like to thank Alex Miller for manuscript revisions. This work was supported with the research grants awarded to M.G. from Cure CMD, Struggle Against Muscular Dystrophy (SAM) and Muscular Dystrophy Association (218938).

1. Tissue Harvest and Freezing of Muscle Tissues
<ol>
	<li>Euthanize the mouse with an overdose of isoflurane (2-chloro-2-(difluoromethoxy)-1,1,1-trifluoro-ethane). Perform this step in a fume hood and use a secondary containment method such as a desiccator or a bell jar containing a cotton swab soaked in isoflurane.</li>
	<li>Confirm death by firmly squeezing footpad. Use a secondary method of euthanasia such as cervical dislocation.</li>
	<li>Wet the fur with 70% alcohol to reduce the sticking of loose hair strands o...

<ol>
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History, clinical status, muscle strength, and biopsy findings.</a> AMA J Dis Child. 91, 326-338 (1956).</li><li>Platzer, A. C., Chase, W. 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Histology and immunohistochemistry have been used as key tools in understanding the manifestation and progression of pathology in various neuromuscular disorders. Classically, muscle biopsies were first fixed in formaldehyde and then embedded with paraffin wax. While formaldehyde fixation preserves tissue architecture and allows tissue storage and transport at RT, it also inactivates enzymes and crosslinks proteins necessitating further steps to achieve accurate immunostaining. This problem is eliminated with the use of ...

Examination of muscle histology plays a critical role in the understanding of different types of neuromuscular disorders1-4. When combined with other techniques, it allows researchers to get a better idea of the manifestation and progression of pathology and can also be essential to evaluate the efficacy of a therapeutic intervention5-10. However, to be accurate, the tissues need to be preserved in the proper manner so as to preserve the physiological state immediately before excision. This requires great care during removal, preservation, sectioning, and staining.
Tissues can be prepared in two different ways for light microscopic study. The first method, formalin fixed paraffin embedded (FFPE) sections, requires tissues to be fixed in 10% natural buffered formaldehyde before being embedded with paraffin wax11,12. The fixation step helps to preserve morphology better but also cross links endogenous proteins thus necessitating intricate antigen retrieval procedures for immunostaining and eliminating the possibility of enzymatic staining on such sections12. Frozen sections, on the other hand, do not need to be pre-fixed or processed; therefore, proteins are able to retain native biological conformations13,14. Further, frozen sections also allow for quick turnaround time, which at times is necessary, for example in the intraoperative diagnosis of sarcomas and other surgical biopsies15. However, if not done properly, this method is prone to freeze damage, which introduces changes to muscle architecture making the sections unfit for histological examination. This paper will outline the most effective method to prepare muscle biopsies in order to achieve optimal staining for proper examination.

<table border="0" cellpadding="0" cellspacing="0">
	<tbody>
		<tr>
			<td>Cryostat</td>
			<td>Leica CM 1850&#160;</td>
			<td>Leica Microsystems Inc.</td>
			<td>Buffalo Grove, IL 60089 United States, office phone 1-800 248 0123 
			Richard Allen Scientific</td>
		</tr>
		<tr>
			<td>Microscope</td>
			<td>Nikon Eclipse 50i&#160;</td>
			<td>Nikon Instruments Inc.</td>
			<td>1300 Walt Whitman Road, Melville, N.Y. 11747-3064, U.S.A. 
			Phone: +1-631-547-8500 
			Olympus</td>
		</tr>
		<tr>
			<td>Image analysis software</td>
			<td>Nikon Imaging Software Basic Research</td>
			<td>Nikon Instruments Inc.</td>
			<td>1300 Walt Whitman Road, Melville, N.Y. 11747-3064, U.S.A. 
			Phone: +1-631-547-8500 
			Image J, Metamorph</td>
		</tr>
		<tr>
			<td>Isoflurane</td>
			<td>14043-220-05</td>
			<td>JD Medical Dist. Co., Inc.</td>
			<td>JD Medical Distrubuting Co., Inc 1923 West Peoria Avenue Phoenix, Arizona 85029</td>
		</tr>
		<tr>
			<td>OCT</td>
			<td>4583</td>
			<td>Sakura Inc.</td>
			<td>Sakrua Fintek, USA, Torrence, CA 90501, USA 
			Leica Microsystem</td>
		</tr>
		<tr>
			<td>Freeze It</td>
			<td>23-022524</td>
			<td>Thermofisher</td>
			<td>790 Memorial Dr, Cambridge, MA, USA, 02139 
			VWR Scientific</td>
		</tr>
		<tr>
			<td>Disposable tissue mold</td>
			<td>22-363-554</td>
			<td>Thermofisher</td>
			<td>790 Memorial Dr, Cambridge, MA, USA, 02139 
			VWR Scientific</td>
		</tr>
		<tr>
			<td>Colorfrost plus slides</td>
			<td>9991001</td>
			<td>Thermofisher</td>
			<td>790 Memorial Dr, Cambridge, MA, USA, 02139 
			VWR Scientific</td>
		</tr>
		<tr>
			<td>Acetone</td>
			<td>650501-4L</td>
			<td>Sigma-Aldrich</td>
			<td>3050 Spruce Street, St.Louis MO, 63103 
			VWR Scientific</td>
		</tr>
		<tr>
			<td>Ethyl alcohol</td>
			<td>HC-1300-1GL</td>
			<td>Thermofisher</td>
			<td>790 Memorial Dr, Cambridge, MA, USA, 02139 
			VWR Scientific</td>
		</tr>
		<tr>
			<td>2-methyl butane</td>
			<td>M 32631-SL</td>
			<td>Sigma-Aldrich</td>
			<td>3050 Spruce Street, St.Louis MO, 63103 
			VWR Scientific</td>
		</tr>
		<tr>
			<td>Xylene</td>
			<td>HC-7001GA</td>
			<td>Thermofisher</td>
			<td>790 Memorial Dr, Cambridge, MA, USA, 02139 
			VWR Scientific</td>
		</tr>
		<tr>
			<td>Cytoseal 280</td>
			<td>8311-4</td>
			<td>Thermofisher</td>
			<td>790 Memorial Dr, Cambridge, MA 02139 
			VWR Scientific</td>
		</tr>
		<tr>
			<td>Hematoxylin Gill #3</td>
			<td>CS402-1D</td>
			<td>Thermofisher</td>
			<td>790 Memorial Dr, Cambridge, MA, USA, 02139 
			VWR Scientific</td>
		</tr>
		<tr>
			<td>Eosin</td>
			<td>6766007</td>
			<td>Thermofisher</td>
			<td>790 Memorial Dr, Cambridge, MA, USA, 02139 
			VWR Scientific</td>
		</tr>
	</tbody>
</table>

do's and don'ts in the preparation of muscle cryosections for histological analysis

Histological evaluation of muscle biopsies has served as an indispensable tool in the understanding of the development and progression of pathology of neuromuscular disorders. However, in order to do so, proper care needs to be taken when excising and preserving tissues to achieve optimal staining. One method of tissue preservation involves fixing tissues in formaldehyde and then embedding them with paraffin wax. This method preserves morphology well and allows for long-term storage at RT but is cumbersome and requires handling of toxic chemicals. Further, formaldehyde fixation results in antigen cross-linking, which necessitates antigen retrieval protocols for effective immunostaining. On the contrary, frozen sectioning does not require fixation and thus retains biological antigen conformation. This method also provides a distinct advantage in quick turn around time, making it especially useful in situations needing quick histological evaluation like intraoperative surgical biopsies. Here we describe the most effective method of preparing muscle biopsies for visualization with different histological and immunological stains.

The set-up for harvesting and freezing of tissues can be seen in Figure 1. Excised tissues should be stored on a gauze soaked in PBS to avoid drying (Figure 1A). When tissues are selected to be used for histological analysis they should be dipped in OCT and laid out on cryo mold in the proper orientation and as close to physiological length as possible to ensure accurate morphology (Figure 1B). Slurry of isopentane suitable for tissue freezing can be achieved by cooling ...

Watch this Scientific Journal Video about Do's and Don'ts in the Preparation of Muscle Cryosections for Histological Analysis at JoVE.com

Do&#039;s and Don&#039;ts in the Preparation of Muscle Cryosections for Histological Analysis

Here we demonstrate the most efficient methods for freezing, embedding, cryosectioning, and staining of muscle biopsies to avoid freezing artifacts.

Do's and Don'ts in the Preparation of Muscle Cryosections for Histological Analysis

Histological evaluation of muscle biopsies has served as an indispensable tool in the understanding of the development and progression of pathology of ...

do-s-don-ts-preparation-muscle-cryosections-for-histological

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31.2K Views.  Boston University. Here we demonstrate the most efficient methods for freezing, embedding, cryosectioning, and staining of muscle biopsies to avoid freezing artifacts.