Name: changes in mammary gland morphology and breast cancer risk in rats
Uploaded: 2010-10-16T17:00:00
Duration: 9 min 36 s
Description: Watch this Scientific Journal Video about Changes in Mammary Gland Morphology and Breast Cancer Risk in Rats at JoVE.com

NCI (U54 CA00100970), NCI (1 R03 CA150040-01), ACS(116602-PF-09-018-01-CNE)

1. Removal of the Abdominal Mammary Gland and Preparing a Whole Mount
<ol>
 <li>Euthanize the animal according to the IACUC guidelines. Pin the animal on its back from its legs with needles, or tape the legs onto the surface board , and wipe the skin wet with ethanol (EtOH). Lift the skin a little bit with forceps and with sharp scissors make a midline incision into the skin starting between the pair #5 nipples and cut towards the neck . Make an inverted Y incision from the midline towards the hind legs . If thoracic mammary glands are also to be collected, make also an Y incision from the midline between the pair #2 nipples towards the front legs.</li>
 <li>Dissect the skin open with scissors on one side of the inverted Y incision to expose the abdominal #4 mammary gland; the mammary glands are attached to the skin. Pin the skin with needles onto the surface board , to completely expose the gland. Work one side and gland at the time.</li>
 <li>Dissect the mammary gland free from the skin either using sharp scissors and/or a scalpel, starting from the proximal area close to the nipple and working towards the distal end of the gland towards the spine of the animal . (This can take several minutes, especially in an older rat.)</li>
 <li>Immediately spread the detached gland onto an appropriately labeled glass slide (use a proper permanent marker pen and/or 'a diamond pen'), and spread the gland carefully corresponding to its original size and shape in situ . The glass slide must be bigger than the gland. After spreading the gland onto the slide, let it sit on the table for a while, so that the gland sticks onto the slide, but don't let it dry.</li>
 <li>Put the slide into a jar containing Carnoy's fixative (75% glacial acetic acid, 25% absolute ethanol=EtOH) , let it get fixed at room temperature (RT) in the fume hood for 2 days or longer. Slides can also be left in the fixative for a longer period of time.</li>
 <li>Wash the slides in 70% EtOH for 1 hour at RT.</li>
 <li>Rinse in distilled water for 30 min at RT.</li>
 <li>Stain in Carmine Alum stain*) for 2 days or longer (until you see that the lymph nodes have stained through; look at the back side of the slide).</li>
 <li>Wash in increasing series of EtOH, 1 hour in each: 70% -&gt; 95% -&gt; 100% . After the last wash in absolute EtOH put the glands in xylene . Let sit in the fume hood in RT at least for 2 days. This last step is clearing of the mammary gland meaning delipidation of the mammary fat pad, and subsequent increase in transparency. The fattier the gland is the longer clearing time is required.</li>
 <li>Mount with cover-slips using a mounting media, such as Permount . Let the slides dry well (several days) before observing under a stereo microscope. *Carmine Alum Stain: Place 1 g carmine (Sigma C1022) and 2.5 g aluminum potassium sulfate (Sigma A7167) in 500 mL distilled water and boil for 20 min. Adjust final volume to 500 mL with water. Filter and refrigerate. Solution can be used for several months. Discard when color becomes weak.</li>
</ol>
2. Analysis of Mammary Gland Whole Mount Morphology
Mammary gland whole mounts morphology is analyzed according to the following end-points and the results correlated with mammary cancer risk.
<ol>
 <li>Mammary gland whole-mount at PND 21 (pre-pubertal age):
 <ul>
 <li>Epithelial growth:
 <ul>
 <li>Distance from the nipple to the end of epithelial tree (in millimeters), measured using a ruler</li>
 </ul>
 </li>
 <li>Potential for malignant transformation:
 <ul>
 <li>Number of TEBs (terminal end buds), counted under a light microscope . TEBs are the largest bulbous structures located only at the distal end of the mammary epithelial tree</li>
 </ul>
 </li>
 <li>Differentiation:
 <ul>
 <li>AB1 (alveolar bud) score (0-5). Alveolar buds are spread across the epithelium.</li>
 <li>AB2 score (0-5)</li>
 </ul>
 </li>
 </ul>
 Wholes mounts are scored under a light microscope. The score values from AB1 and AB2 are added for a final differentiation score.</li>
 <li>Mammary gland whole-mount collected at PND 50 (post-pubertal age) :
 <ul>
 <li>Epithelial growth:
 <ul>
 <li>Distance from the lymph node to the end of epithelial tree (in millimeters), measured using a ruler.</li>
 <li>Distance from the tip of the epithelial tree to the end of fat pad, measured using a ruler.</li>
 </ul>
 </li>
 <li>Potential for malignant transformation:
 <ul>
 <li>Number of TEBs, counted under a light microscope</li>
 </ul>
 </li>
 <li>Differentiation:
 <ul>
 <li>AB1 score (0-5)</li>
 <li>AB2 score (0-5)</li>
 <li>Lobules score (0-5)</li>
 </ul>
 </li>
 </ul>
 
 Wholes mounts are scored under a light microscope. Differentiation will be assesses in two ways. First, the score values from AB1, AB2 and lobules are added for a final differentiation score. In addition, the ratio between lobules score and AB1+AB2 score will be calculated. ABs differentiate to lobules, and the higher the ratio between lobules and ABs, the more differentiated the gland is. </li>
</ol>
3. Palpation and Mammary Tumor Measurement in Rats and Correlation to Mammary Gland Morphology
<ol>
<li>To begin this procedure, hold the rat by grasping the whole body with the palm over the back, with forefinger behind the head and the thumb and second finger under the opposite axilla. Turn the rat so it is lying on its posterior, and palpate to detect any mammary tumors; palpable tumors should feel like a "lump".</li>
<li>Next use a caliper to measure the width, length, and height of the tumor. Calculate the tumor volume using the ellipsoid formula, Volume =1/6&pi;abc, where 'a'= width, 'b' = length, and 'c' = height.</li>
<li>Manually record the location and size of the tumor in a notebook on a weekly basis. This data will be transferred to a spreadsheet later.</li>
</ol>
4. Representative Results
Careful dissection of the mammary fat pad and its processing to wholemount will allow assessment of developmental state of the mammary gland. When each step is done correctly, the whole mammary epithelial tree is clearly visible within the fat pad, and this allows easy determination of the number of TEBs and calculation of the density of alveolar buds and lobules. Missteps in preparing wholemounts may include failure to dissect the whole fat pad, insufficient fixing, and inadequate clearing.
Assessment of mammary gland morphology will provide information about the number of structures present that can give rise to mammary tumors (TEBs), degree of differentiation of the epithelial structures (alveolar buds and lobules), and measure of growth (ductal elongation). It is important to separate TEBs to terminal ends; the latter are located at the distal end of the epithelium, similarly to TEBs, but they are smaller than TEBs and do not give rise to malignant tumors. Terminal ends are also seen within the epithelial tree.
<img src="/files/ftp_upload/2260/2260fig1.jpg" alt="Figure 1" /> Figure 1: Representative result of well prepared mammary gland whole mount. All components of the gland have been properly dissected and carmine staining is optimal.
<img src="/files/ftp_upload/2260/2260fig2.jpg" alt="Figure 2" /> Figure 2: Representative result of a poorly prepared mammary gland whole mount. The gland has been properly dissected (the distal portion of the gland is missing), has not been properly stretched and delipidation has not completely occurred.

<ol>
	<li>Rasmussen, S. B., Young, L. J. T., Smith, G. H., Ip, M. M., Asch, B. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Preparing+mammary+gland+whole+mounts+form+mice.">Preparing mammary gland whole mounts form mice.</a> Methods in Mammary Gland Biology and Breast Cancer Research. , 75-85 (2000).</li><li>. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Consensus+statements+from+Mammary+Gland+Whole+Mount+Round+Robin+meeting.">Consensus statements from Mammary Gland Whole Mount Round Robin meeting.</a> , (2009).</li><li>Hilakivi-Clarke, L., Clarke, R., Onojafe, I., Raygada, M., Cho, E., &amp;amp, L. i. p. p. m. a. n., E, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+maternal+diet+high+in+n-6+polyunsaturated+fats+alters+mammary+gland+development,+puberty+onset,+and+breast+cancer+risk+among+female+rat+offspring.">A maternal diet high in n-6 polyunsaturated fats alters mammary gland development, puberty onset, and breast cancer risk among female rat offspring.</a> Proc Natl Acad Sci. 94, 9372-9377 (1997).</li><li>Russo, I. H., Russo, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mammary+gland+neoplasia+in+long-term+rodent+studies.">Mammary gland neoplasia in long-term rodent studies.</a> Environ. Health Perspect. 104 (9), 938-967 (1996).</li><li>Hilakivi-Clarke, L., de Assis, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fetal+origins+of+breast+cancer.">Fetal origins of breast cancer.</a> TRENDS in Endocrinol and Metabol. 17 (9), 340-348 (2006).</li><li>Hilakivi-Clarke, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nutritional+modulation+of+terminal+end+buds:+its+relevance+to+breast+cancer+prevention.">Nutritional modulation of terminal end buds: its relevance to breast cancer prevention.</a> Curr Cancer Drug Targets. 7 (4), 465-474 (2007).</li><li>Silva Idos, S., De Stavola, B., Mccormack, V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Collaborative+Group+On+Pre-Natal+Risk+Factors+And+Subsequent+Risk+Of+Breast+Cancer.+Birth+size+and+breast+cancer+risk:+re-analysis+of+individual+participant+data+from+32+studies.">Collaborative Group On Pre-Natal Risk Factors And Subsequent Risk Of Breast Cancer. Birth size and breast cancer risk: re-analysis of individual participant data from 32 studies.</a> PloS Medicine. 5, e193-e193 (2008).</li><li>Warri, A., Saarinen, N. M., Makela, S., Hilakivi-Clarke, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+early+life+genistein+exposures+in+modifying+breast+cancer+risk.">The role of early life genistein exposures in modifying breast cancer risk.</a> Br J Cancer. 98, 1485-1493 (2008).</li><li>Russo, J., Hu, Y. F., Yang, X., Russo, I. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Developmental,+cellular,+and+molecular+basis+of+human+breast+cancer.">Developmental, cellular, and molecular basis of human breast cancer.</a> J Natl Cancer Inst Monogr. , 17-37 (2000).</li><li>Oza, A. M., Boyd, N. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Mammographic+parenchymal+patterns:+A+marker+of+breast+cancer+risk.">Mammographic parenchymal patterns: A marker of breast cancer risk.</a> Epidemiological Reviews. 15, 196-208 (1993).</li></ol>

No conflicts of interest declared.

Assessment of mammary gland morphological end-points and the growth of the epithelial tree can be used to predict whether early life dietary manipulations, or other manipulations which alter in utero or prepubertal hormonal environment, modify later mammary cancer risk. Since breast cancer in humans is initiated in mammary structures (terminal ductal lobular units, TDLUs) similar to TEBs in rats, this technique can be used to determine the potential of early life exposures to affect breast cancer risk. Further, in women high mammographic density increases the risk of breast cancer by 4-6 fold, and assessment of the growth of mammary epithelial tree can be used to identify factors which determine mammographic density and factors which reduce this density. To obtain this information, mammary gland should be fully dissected, properly stretched on a glass slide so that all its components can be visualized under a microscope. In addition, proper carmine staining and delipidation in xylene will provide whole mounts that are suitable for mammary cancer risk assessment.

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		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
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<td>Glacial acetic acid</td>
<td>&nbsp;</td>
<td>EM</td>
<td>AX0073-9</td>
<td>Carnoy's Fixative</td>
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<td>Absolute ethanol</td>
<td>&nbsp;</td>
<td>The Waner-Graham Co.</td>
<td>64-17-5</td>
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<td>Carmine</td>
<td>&nbsp;</td>
<td>Sigma</td>
<td>C1022</td>
<td>Carmine solution</td>
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<tr>
<td>Aluminum potassium sulfate</td>
<td>&nbsp;</td>
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changes in mammary gland morphology and breast cancer risk in rats

Studies in rodent models of breast cancer show that exposures to dietary/hormonal factors during the in utero and pubertal periods, when the mammary gland undergoes extensive modeling and re-modeling, alter susceptibility to carcinogen-induced mammary tumors. Similar findings have been described in humans: for example, high birthweight increases later risk of developing breast cancer, and dietary intake of soy during childhood decreases breast cancer risk. It is thought that these prenatal and postnatal dietary modifications induce persistent morphological changes in the mammary gland that in turn modify breast cancer risk later in life. These morphological changes likely reflect epigenetic modifications, such as changes in DNA methylation, histones and miRNA expression that then affect gene transcription . In this article we describe how changes in mammary gland morphology can predict mammary cancer risk in rats. Our protocol specifically describes how to dissect and remove the rat abdominal mammary gland and how to prepare mammary gland whole mounts. It also describes how to analyze mammary gland morphology according to three end-points (number of terminal end buds, epithelial elongation and differentiation) and to use the data to predict risk of developing mammary cancer.

Watch this Scientific Journal Video about Changes in Mammary Gland Morphology and Breast Cancer Risk in Rats at JoVE.com

Changes in Mammary Gland Morphology and Breast Cancer Risk in Rats

Our protocol describes how to dissect the rat abdominal mammary gland and how to prepare mammary gland whole mounts. It also describes how to analyze mammary gland morphology using three end-points (number of terminal end buds, epithelial elongation and differentiation) and to use these results to predict mammary cancer risk in rats which were exposed to dietary modifications in utero or during prepuberty.

Studies in rodent models of breast cancer show that exposures to dietary/hormonal factors during the in utero and pubertal periods, when the mammary gland ...

changes-in-mammary-gland-morphology-and-breast-cancer-risk-in-rats

Research

JoVE Journal

Biology

Evaluation of Mammary Gland Development and Function in Mouse Models

The human mammary gland is composed of 15-20 lobes that secrete milk into a branching duct system opening at the nipple. Those lobes are themselves composed of a number of terminal duct lobular units made of secretory alveoli and converging ducts1. In mice, a similar architecture is observed at pregnancy in which ducts and alveoli are interspersed within the connective tissue stroma. The mouse mammary gland epithelium is a tree like system of ducts composed of two layers of cells, an inner layer of luminal cells surrounded by an outer layer of myoepithelial cells denoted by the confines of a basement membrane2. At birth, only a rudimental ductal tree is present, composed of a primary duct and 15-20 branches. Branch elongation and amplification start at the beginning of puberty, around 4 weeks old, under the influence of hormones3,4,5. At 10 weeks, most of the stroma is invaded by a complex system of ducts that will undergo cycles of branching and regression in each estrous cycle until pregnancy2. At the onset of pregnancy, a second phase of development begins, with the proliferation and differentiation of the epithelium to form grape-shaped milk secretory structures called alveoli6,7. Following parturition and throughout lactation, milk is produced by luminal secretory cells and stored within the lumen of alveoli. Oxytocin release, stimulated by a neural reflex induced by suckling of pups, induces synchronized contractions of the myoepithelial cells around the alveoli and along the ducts, allowing milk to be transported through the ducts to the nipple where it becomes available to the pups 8. Mammary gland development, differentiation and function are tightly orchestrated and require, not only interactions between the stroma and the epithelium, but also between myoepithelial and luminal cells within the epithelium9,10,11. Thereby, mutations in many genes implicated in these interactions may impair either ductal elongation during puberty or alveoli formation during early pregnancy, differentiation during late pregnancy and secretory activation leading to lactation12,13. In this article, we describe how to dissect mouse mammary glands and assess their development using whole mounts. We also demonstrate how to evaluate myoepithelial contractions and milk ejection using an ex-vivo oxytocin-based functional assay. The effect of a gene mutation on mammary gland development and function can thus be determined in situ by performing these two techniques in mutant and wild-type control mice.

This method describes how to dissect and assess mammary gland development and function from mice. Excised mammary glands are assessed for the degree of development using whole mount while milk ejection is evaluated using an oxytocin-based myoepithelial cell contraction assay.

The human mammary gland is composed of 15-20 lobes that secrete milk into a branching duct system opening at the nipple. Those lobes are themselves ...

Quantitative Measurement of Invadopodia-mediated Extracellular Matrix Proteolysis in Single and Multicellular Contexts

Cellular invasion into local tissues is a process important in development and homeostasis. Malregulated invasion and subsequent cell movement is characteristic of multiple pathological processes, including inflammation, cardiovascular disease and tumor cell metastasis1. Focalized proteolytic degradation of extracellular matrix (ECM) components in the epithelial or endothelial basement membrane is a critical step in initiating cellular invasion. In tumor cells, extensive in vitro analysis has determined that ECM degradation is accomplished by ventral actin-rich membrane protrusive structures termed invadopodia2,3. Invadopodia form in close apposition to the ECM, where they moderate ECM breakdown through the action of matrix metalloproteinases (MMPs). The ability of tumor cells to form invadopodia directly correlates with the ability to invade into local stroma and associated vascular components3. 
Visualization of invadopodia-mediated ECM degradation of cells by fluorescent microscopy using dye-labeled matrix proteins coated onto glass coverslips has emerged as the most prevalent technique for evaluating the degree of matrix proteolysis and cellular invasive potential4,5. Here we describe a version of the standard method for generating fluorescently-labeled glass coverslips utilizing a commercially available Oregon Green-488 gelatin conjugate. This method is easily scaled to rapidly produce large numbers of coated coverslips. We show some of the common microscopic artifacts that are often encountered during this procedure and how these can be avoided. Finally, we describe standardized methods using readily available computer software to allow quantification of labeled gelatin matrix degradation mediated by individual cells and by entire cellular populations. The described procedures provide the ability to accurately and reproducibly monitor invadopodia activity, and can also serve as a platform for evaluating the efficacy of modulating protein expression or testing of anti-invasive compounds on extracellular matrix degradation in single and multicellular settings.

We describe the prototypical method for producing microscope coverslips coated with fluorescent gelatin for visualizing invadopodia-mediated matrix degradation. Computational techniques using available software are presented for quantifying the resultant levels of matrix proteolysis by single cells within a mixed population and for multicellular groups encompassing entire microscopic fields.

Cellular invasion into local tissues is a process important in development and homeostasis.  Malregulated invasion and subsequent cell movement is ...

An Analytical Tool that Quantifies Cellular Morphology Changes from Three-dimensional Fluorescence Images

The most common software analysis tools available for measuring fluorescence images are for two-dimensional (2D) data that rely on manual settings for inclusion and exclusion of data points, and computer-aided pattern recognition to support the interpretation and findings of the analysis. It has become increasingly important to be able to measure fluorescence images constructed from three-dimensional (3D) datasets in order to be able to capture the complexity of cellular dynamics and understand the basis of cellular plasticity within biological systems. Sophisticated microscopy instruments have permitted the visualization of 3D fluorescence images through the acquisition of multispectral fluorescence images and powerful analytical software that reconstructs the images from confocal stacks that then provide a 3D representation of the collected 2D images. Advanced design-based stereology methods have progressed from the approximation and assumptions of the original model-based stereology1 even in complex tissue sections2. Despite these scientific advances in microscopy, a need remains for an automated analytic method that fully exploits the intrinsic 3D data to allow for the analysis and quantification of the complex changes in cell morphology, protein localization and receptor trafficking. 
Current techniques available to quantify fluorescence images include Meta-Morph (Molecular Devices, Sunnyvale, CA) and Image J (NIH) which provide manual analysis. Imaris (Andor Technology, Belfast, Northern Ireland) software provides the feature MeasurementPro, which allows the manual creation of measurement points that can be placed in a volume image or drawn on a series of 2D slices to create a 3D object. This method is useful for single-click point measurements to measure a line distance between two objects or to create a polygon that encloses a region of interest, but it is difficult to apply to complex cellular network structures. Filament Tracer (Andor) allows automatic detection of the 3D neuronal filament-like however, this module has been developed to measure defined structures such as neurons, which are comprised of dendrites, axons and spines (tree-like structure). This module has been ingeniously utilized to make morphological measurements to non-neuronal cells3, however, the output data provide information of an extended cellular network by using a software that depends on a defined cell shape rather than being an amorphous-shaped cellular model. To overcome the issue of analyzing amorphous-shaped cells and making the software more suitable to a biological application, Imaris developed Imaris Cell. This was a scientific project with the Eidgen&ouml;ssische Technische Hochschule, which has been developed to calculate the relationship between cells and organelles. While the software enables the detection of biological constraints, by forcing one nucleus per cell and using cell membranes to segment cells, it cannot be utilized to analyze fluorescence data that are not continuous because ideally it builds cell surface without void spaces. To our knowledge, at present no user-modifiable automated approach that provides morphometric information from 3D fluorescence images has been developed that achieves cellular spatial information of an undefined shape (Figure 1). 
We have developed an analytical platform using the Imaris core software module and Imaris XT interfaced to MATLAB (Mat Works, Inc.). These tools allow the 3D measurement of cells without a pre-defined shape and with inconsistent fluorescence network components. Furthermore, this method will allow researchers who have extended expertise in biological systems, but not familiarity to computer applications, to perform quantification of morphological changes in cell dynamics.

We developed a software platform that utilizes Imaris Neuroscience, ImarisXT and MATLAB to measure the changes in morphology of an undefined shape taken from three-dimensional confocal fluorescence of single cells. This novel approach can be used to quantify changes in cell shape following receptor activation and therefore represents a possible additional tool for drug discovery.

The most common software analysis tools available for measuring fluorescence images are for two-dimensional (2D) data that rely on manual settings for ...

Combined Immunofluorescence and DNA FISH on 3D-preserved Interphase Nuclei to Study Changes in 3D Nuclear Organization

Fluorescent in situ hybridization using DNA probes on 3-dimensionally preserved nuclei followed by 3D confocal microscopy (3D DNA FISH) represents the most direct way to visualize the location of gene loci, chromosomal sub-regions or entire territories in individual cells. This type of analysis provides insight into the global architecture of the nucleus as well as the behavior of specific genomic loci and regions within the nuclear space. Immunofluorescence, on the other hand, permits the detection of nuclear proteins (modified histones, histone variants and modifiers, transcription machinery and factors, nuclear sub-compartments, etc). The major challenge in combining immunofluorescence and 3D DNA FISH is, on the one hand to preserve the epitope detected by the antibody as well as the 3D architecture of the nucleus, and on the other hand, to allow the penetration of the DNA probe to detect gene loci or chromosome territories 1-5. Here we provide a protocol that combines visualization of chromatin modifications with genomic loci in 3D preserved nuclei.

Here we describe a protocol for simultaneous detection of histone modifications by immunofluorescence and DNA sequences by DNA FISH followed by 3D microscopy and analyses (3D immuno-DNA FISH).

Fluorescent in situ hybridization using DNA probes  on 3-dimensionally preserved nuclei followed by 3D confocal microscopy (3D DNA  FISH) represents the ...

Intraductal Injection for Localized Drug Delivery to the Mouse Mammary Gland

Herein we describe a protocol to deliver various reagents to the mouse mammary gland via intraductal injections. Localized drug delivery and knock-down of genes within the mammary epithelium has been difficult to achieve due to the lack of appropriate targeting molecules that are independent of developmental stages such as pregnancy and lactation. Herein, we describe a technique for localized delivery of reagents to the mammary gland at any stage in adulthood via intraductal injection into the nipples of mice. The injections can be performed on live mice, under anesthesia, and allow for a non-invasive and localized drug delivery to the mammary gland. Furthermore, the injections can be repeated over several months without damaging the nipple. Vital dyes such as Evans Blue are very helpful to learn the technique. Upon intraductal injection of the blue dye, the entire ductal tree becomes visible to the eye. Furthermore, fluorescently labeled reagents also allow for visualization and distribution within the mammary gland. This technique is adaptable for a variety of compounds including siRNA, chemotherapeutic agents, and small molecules.

A protocol for the non-invasive intraductal delivery of aqueous reagents to the mouse mammary gland is described. The method takes advantage of localized injection into the nipples of mammary glands targeting mammary ducts specifically. This technique is adaptable for a variety of compounds including siRNA, chemotherapeutic agents and small molecules.

Herein we describe a protocol to deliver various reagents to the mouse mammary gland via intraductal injections. Localized drug delivery and knock-down of ...

Indirect Immunofluorescence on Frozen Sections of Mouse Mammary Gland

Indirect immunofluorescence is used to detect and locate proteins of interest in a tissue. The protocol presented here describes a complete and simple method for the immune detection of proteins, the mouse lactating mammary gland being taken as an example. A protocol for the preparation of the tissue samples, especially concerning the dissection of mouse mammary gland, tissue fixation and frozen tissue sectioning, are detailed. A standard protocol to perform indirect immunofluorescence, including an optional antigen retrieval step, is also presented. The observation of the labeled tissue sections as well as image acquisition and post-treatments are also stated. This procedure gives a full overview, from the collection of animal tissue to the cellular localization of a protein. Although this general method can be applied to other tissue samples, it should be adapted to each tissue/primary antibody couple studied.

The indirect immunofluorescence protocol described in this article allows the detection and the localization of proteins in the mouse mammary gland. A complete method is given to prepare mammary gland samples, to perform immunohistochemistry, to image the tissue sections by fluorescence microscopy, and to reconstruct images.

Indirect immunofluorescence is used to detect and locate proteins of interest in a tissue. The protocol presented here describes a complete and simple ...

Comparison of Three Different Methods for Determining Cell Proliferation in Breast Cancer Cell Lines

Measuring cell proliferation can be performed by a number of different methods, each with varying levels of sensitivity, reproducibility and compatibility with high-throughput formatting. This protocol describes the use of three different methods for measuring cell proliferation in vitro including conventional hemocytometer counting chamber, a luminescence-based assay that utilizes the change in the metabolic activity of viable cells as a measure of the relative number of cells, and a multi-mode cell imager that measures cell number using a counting algorithm. Each method presents its own advantages and disadvantages for the measurement of cell proliferation, including time, cost and high-throughput compatibility. This protocol demonstrates that each method could accurately measure cell proliferation over time, and was sensitive to detect growth at differing cellular densities. Additionally, measurement of cell proliferation using a cell imager was able to provide further information such as morphology, confluence and allowed for a continual monitoring of cell proliferation over time. In conclusion, each method is capable of measuring cell proliferation, but the chosen method is user-dependent.

This protocol describes the use of three different methods for analyzing cell proliferation in breast cancer cell lines. This includes the use of conventional cell counting, luminescence-based cell viability, and cell counting through the use of a cell imager. Each offers advantages for the reproducible measurement of cell proliferation.

Measuring cell proliferation can be performed by a number of different methods, each with varying levels of sensitivity, reproducibility and compatibility ...

Isolation of Intact, Whole Mouse Mammary Glands for Analysis of Extracellular Matrix Expression and Gland Morphology

The goal of this procedure was to harvest the #4 abdominal mammary glands from female nulliparous mice in order to assess ECM expression and ductal architecture. Here, a small pocket below the skin was created using Mayo scissors, allowing separation of the glands within the subcutaneous tissue from the underlying peritoneum. Visualization of the glands was aided by the use of 3.5x-R surgical micro loupes. The pelt was inverted and pinned back allowing identification of the intact mammary fat pads. Each of the #4 abdominal glands was bluntly dissected by sliding the scalpel blade laterally between the subcutaneous layer and the glands. Immediately post-harvest, glands were placed in 10% neutral buffered formalin for subsequent tissue processing. Excision of the entire gland is advantageous because it primarily eliminates the risk of excluding important tissue-wide interactions between ductal epithelial cells and other microenvironmental cellular populations that could be missed in a partial biopsy. One drawback of the methodology is the use of serial sections from fixed tissues which limits analyses of ductal morphogenesis and protein expression to discrete locations within the gland. As such, changes in ductal architecture and protein expression in 3 dimensions (3D) is not readily obtainable. Overall, the technique is applicable to studies requiring whole intact murine mammary glands for downstream investigations such as developmental ductal morphogenesis or breast cancer.

Here, we present a protocol for the isolation of whole, intact mouse mammary glands to investigate extracellular matrix (ECM) expression and ductal morphology. Mouse #4 abdominal glands were extracted from 8-10 week old female nulliparous mice, fixed in neutral buffered formalin, sectioned and stained using immunohistochemistry for ECM proteins.

The goal of this procedure was to harvest the #4 abdominal mammary glands from female nulliparous mice in order to assess ECM expression and ductal ...

Bovine Mammary Gland Biopsy Techniques

Bovine mammary gland biopsies allow researchers to collect tissue samples to study cell biology including gene expression, histological analysis, signaling pathways, and protein translation. This article describes two techniques for biopsy of the bovine mammary gland (MG). Three healthy Holstein dairy cows were the subjects. Before biopsies, cows were milked and subsequently restrained in a cattle chute. An analgesic (flunixin meglumine, 1.1 to 2.2 mg/kg of body weight) was administered via jugular intravenous [IV] injection 15-20 min prior to biopsy. For standing sedation, xylazine hydrochloride (0.01-0.05 mg/kg of body weight) was injected via the coccygeal vessels 5-10 min before the procedure. Once adequately sedated, the biopsy site was aseptically prepared and locally anaesthetized with 6 mL of 2% lidocaine hydrochloride via subcutaneous injection. Using aseptic technique, a 2 to 3 cm vertical incision was made using a number 10 scalpel. Core and needle biopsy tools were used. The core biopsy tool was attached to a cordless drill and inserted into the MG tissue through the incision using a clock-wise drill action. The needle biopsy tool was manually inserted into the incision site. Immediately after the procedure, an assistant applied pressure on the incision site for 20 to 25 min using a sterile towel to achieve hemostasis. Stainless steel surgical staples were used to oppose the skin incision. The staples were removed 10 days post-procedure. The main advantages of core and needle biopsies is that both approaches are minimally invasive procedures that can be safely performed in healthy cows. Milk yield following the biopsy was unaffected. These procedures require a short recovery time and result in fewer risks of complications. Specific limitations may include bleeding after the biopsy and infection on the biopsy site. Applications of these techniques include tissue collection for clinical diagnosis and research purposes, such as primary cell culture.

This article presents a bovine mammary gland biopsy using core and needle biopsy tools. Harvested tissue can be used for cell culture or to assess mammary physiology and metabolism including gene expression, protein expression, protein modifications, immunohistochemistry, and metabolite concentrations.

Bovine mammary gland biopsies allow researchers to collect tissue samples to study cell biology including gene expression, histological analysis, ...

Longitudinal Intravital Microscopy Using a Mammary Imaging Window with Replaceable Lid

The branched structure of the mammary gland is highly dynamic and undergoes several phases of growth and remodeling after birth. Intravital microscopy in combination with skin flap surgery or implantation of imaging windows has been used to study the dynamics of the healthy mammary gland at different developmental stages. Most mammary imaging technologies are limited to a time frame of hours to days, whereas the majority of mammary gland remodeling processes occur in time frames of days to weeks. To study mammary gland remodeling, methods that allow optical access to the tissue of interest for extended time frames are required. Here, an improved version of the titanium mammary imaging window with a replaceable lid (R.MIW) is described that allows high-resolution imaging of the mammary gland with a cellular resolution for up to several weeks. Importantly, the R.MIW provides tissue access over the entire duration of the intravital imaging experiment and could therefore be used for local tissue manipulation, labeling, drug administration, or image-guided microdissection. Taken together, the R.MIW enables high-resolution characterization of the cellular dynamics during mammary gland development, homeostasis, and disease.

This protocol describes a novel mammary imaging window with a replaceable lid (R.MIW). Intravital microscopy after implantation of the R.MIW allows for longitudinal and multi-day imaging of the healthy and diseased mammary gland with a cellular resolution during the different developmental stages.

The branched structure of the mammary gland is highly dynamic and undergoes several phases of growth and remodeling after birth. Intravital microscopy in ...