The authors thank Leif Oxburgh and Derek Adams for generously sharing their knowledge, Leif Oxburgh for the helpful comments on the manuscript, and Stefan W&#246;lfl and Ulrike M&#252;ller for their technical support and Saskia Schmitteckert , Julia Gobbert, Sascha Weyer and Viola Mayer for help in the lab. This work was supported by Development, The Company of Biologists(to CP).

Mice were maintained according to Swedish regulations and European Union legislation (2010/63/EU). All procedures were performed following the guidelines of the Swedish Ethics Committee (permits C79/9, C248/11, and C135/14). Procedures at Heidelberg University involving animal subjects have been approved by the Regierungspr&#228;sidium Karlsruhe and the Animal Welfare Officers at the University of Heidelberg.
1. Preparation of Reagents and Materials for Culture
NOTE : Use a laminar flow hood to minimize contamination.
<ol>
	<li>On the day of dissection, pre-cluster human Fc alone or recombinant chimeric ephrin protein fused to human Fc by mixing it with anti-human Fc goat antibodies at a molar ratio of 1:5 in sterile phosphate-buffered saline (PBS). Incubate for 1 h at 37 &#176;C5.</li>
	<li>Prepare the culture medium by supplementing Dulbecco&#39;s Modified Eagle Medium: Nutrient Mixture F-12 (DMEM/F12) with 1% penicillin/streptomycin (v/v), 1% glutamine (v/v), 1% insulin-transferrin-selenium (v/v), 50 &#181;g/mL human holo-transferrin, and 1.5 &#181;g/mL amphotericin. 
	NOTE: 10 mL of medium is sufficient for 16 embryos.</li>
	<li>Add clustered recombinant ephrin solution at a final concentration of 20 &#181;g/mL to the culture medium. Use clustered human Fc as control.</li>
	<li>Prepare culture plates by adding 500 &#181;L of culture medium to each well of a sterile, uncoated, flat-bottom polystyrene 4-well plate.</li>
	<li>Using sterile forceps, carefully place one polycarbonate membrane filter with a pore size of 5 &#181;m per well on top of the medium. Transfer the prepared plate to the incubator (37 &#176;C/5% CO2). Ensure that the filter stays dry on the upper surface and floats. 
	NOTE: One filter is sufficient for two kidney anlagen.</li>
	<li>Using a razor blade, cut approximately 30 pipette tips (volume: 100 &#181;L) approximately 1 mm from the tip to result in a wider opening. Place the tips back into a pipette-tip rack.</li>
</ol>
2. Dissection of Metanephric Rudiments at E11.5
<ol>
	<li>Sacrifice a timed-pregnant mouse at E11.5 by cervical dislocation (or using a method approved by the local ethics committee).</li>
	<li>Remove the uterus and the embryos, as described by Brown et al 6. From this point forward, work under a dissection microscope.</li>
	<li>Using No. 5 watchmaker forceps, cut the embryo directly under the forelegs. Use a fresh petri dishfor each embryo. Remove the legs and the tail of the embryo. To do this, grab the tissue to be removed with one pair of No. 5 watchmaker forceps and use the tips of a second pair to cut.</li>
	<li>To remove the ventral organ mass, use the tips of a pair of forceps to laterally open the body wall of the embryo in a rostral-to-caudal direction.
	<ol>
		<li>Cut superficially, parallel to the dorsal aorta. Use the blood-filled and therefore visible dorsal aorta for orientation. Carefully separate the ventral part of the body wall from the dorsal part using the tips of closed forceps and flip the embryo over. Cut the body wall laterally in a rostral-to-caudal direction and using the dorsal aorta for orientation, as for the previous side.</li>
	</ol>
	</li>
	<li>Once the ventral body wall has been separated from the dorsal body, grab it with one pair of forceps and carefully pull to remove it, together with the organ mass. 
	NOTE: The metanephric anlagen usually stay attached to the dorsal body wall. They are oval, ~ 200 &#181;m long structures located at the level of the hind limbs.</li>
	<li>Hold the dorsal body wall with one pair of forceps, with the ventral side facing up. Using the other pair of forceps, grab the dorsal aorta at its rostral end and carefully peel the dorsal aorta from the dorsal body wall. 
	NOTE: Both metanephric kidneys usually stay attached to the dorsal aorta.</li>
	<li>Using one pair of forceps, cut rostrally to the kidney anlagen to remove the aorta. Then, carefully separate the two kidney anlagen using the tips of the forceps.</li>
	<li>Carefully peel off unwanted tissue from the kidney anlagen using the tips of the forceps. Take care not to damage the mesenchyme, as damage can result in poor growth and exclusion of the explant from further analysis.</li>
	<li>Transfer the kidney anlagen separately using a microliter pipette and a wide-open pipette tip in 10 &#181;L of PBS to the polycarbonate membrane filter in a 4-well-plate. 
	NOTE: Due to surface tension, the explant will be covered with a thin layer of medium. One filter is sufficient for two kidney anlagen.
	<ol>
		<li>Place each of the two kidney anlagen at the center of each respective half of the filter. Transfer the plate back to the incubator at 37 &#176;C/5% CO2. Leave the plate in the incubator until the metanephric rudiments from the next embryo are ready to be placed on the filter.</li>
	</ol>
	</li>
	<li>Repeat steps 2.3-2.9.1 for each embryo. 
	NOTE: With some practice, the dissection procedure will take about 5 min per embryo.</li>
	<li>Incubate the kidney anlagen for 3 days at 37 &#176;C/5% CO2.</li>
</ol>
3. Preparation of Reagents for Fixation and Staining
<ol>
	<li>To prepare 4% paraformaldehyde (PFA) in PBS without calcium and magnesium (w/v), dissolve the PFA at 60 &#176;C in PBS, continuously stirring. Cool to room temperature and use a paper filter to remove the remaining particles. Aliquot and keep at 4 &#176;C for immediate use or freeze for long-term storage. 
	CAUTION: PFA is toxic. Wear the personal protective equipment specified in the local safety standards and work in a fume hood. Discard waste following institutional guidelines and using designated waste containers.</li>
	<li>To prepare permeabilization solution, dilute Triton X-100 in PBS without calcium and magnesium to 0.3% (v/v).</li>
	<li>To prepare blocking solution, add 5% (v/v) goat serum and 0.1% Triton X-100 to PBS without calcium and magnesium. Add sodium azide to a final concentration of 0.02% (w/v). Store at 4 &#176;C. 
	CAUTION: Sodium azide is toxic. Handle sodium azide in accordance with the local safety and environmental protection regulations. 
	NOTE: When using antibodies for staining, use 5% serum from the species the secondary antibody was derived from to make blocking solution.</li>
	<li>Dilute biotinylated Dolichorus biflorus agglutinin 1:200 in blocking solution. Dilute Alexa488-conjugated streptavidin 1:200 in blocking solution.</li>
	<li>To make ready-to-use embedding medium (see the table of materials), add 0.1 g of water-soluble polyvinyl alcohol-based mucoadhesive/mL to 25% (w/v) glycerol in 0.1 M Tris-HCl (pH 8.5). Heat to 50 &#176;C under continuous agitation for 1 h, cool down, and adjust the pH to 8.0-8.5 using 1 M NaOH. Avoid higher NaOH concentrations. Add 100 &#181;g/mL N-propylgallate and thimerosal to a final concentration of 0.02% (w/v). Stir for 30 min at room temperature. 
	CAUTION: Thimerosal is toxic. Handle it in accordance with the local safety and environmental protection regulations.
	<ol>
		<li>Fill the embedding medium in 50 mL tubes, balance the rotor, and centrifuge at 3,200 x g and room temperature for 10 min. Decant the clear solution into 15 mL tubes and discard the pellet. Aliquot and store at -20 &#176;C for several weeks. Once thawed, keep the solution at 4 &#176;C. Warm to ~30 &#176;C immediately before use.</li>
	</ol>
	</li>
	<li>Prepare as many glass slides as filters with explants are to be mounted. For this, glue two small coverslips, 18 x 18 mm, on either side of the glass slide using instant adhesive, Leave a ~15 mm space for the filter in between.</li>
</ol>
4. Fixation and staining
<ol>
	<li>After a culturing period of 3 days in vitro (div), remove the plates from the incubator and carefully aspirate the culture medium from each well using a micropipette. Make sure not to touch the filter and keep the tip opening towards the wall of the well.</li>
	<li>Add 500 &#181;L of 4% PFA/PBS to each well. The filters will float on the fixative. Using a micropipette, carefully add the PFA fixative dropwise to submerge the filters. Incubate at room temperature for 30 min. 
	NOTE: For all following steps, care must be taken not to wash off the explants from the filter. Keep the opening of the pipette tip towards the wall of the well.</li>
	<li>Remove the PFA and rinse twice with 500 &#181;L of PBS, submerging the filter. Add 500 &#181;L of permeabilization solution to each well and incubate at room temperature for 1 h.</li>
	<li>Rinse twice with 500 &#181;L of PBS and add 500 &#181;L of blocking solution to each well. Incubate at room temperature for 1 h.</li>
	<li>Replace the blocking solution with 250 &#181;L of biotinylated Dolichorus biflorus agglutinin diluted 1:200 in blocking solution and incubate at 4 &#176;C for 24 h.</li>
	<li>Remove the Dolichorus biflorus agglutinin solution and rinse twice with 500 &#181;L of PBS per well.</li>
	<li>Add 250 &#181;L of Alexa488-conjugated streptavidin diluted 1:200 in blocking solution and incubate at 4 &#176;C for 24 h. Alternatively, incubate at room temperature for 2 h. 
	NOTE: A better signal-to-noise ratio is achieved when incubated at 4 &#176;C.</li>
	<li>Rinse twice with 500 &#181;L of PBS per well. Using forceps, transfer the filters to the prepared glass slides, with the explants facing up. Mount with ~50-100 &#181;L of embedding medium. Cover with 60 mm-long No. 1.5 coverslips. Allow the embedding medium solution to solidify for 2 h at room temperature in the dark. Proceed to imaging or store the slides, wrapped in foil, at 4 &#176;C until ready to image.</li>
	<li>Image with a widefield epifluorescence microscope7 coupled to an Hg-lamp and use a mirror unit for blue excitation (excitation bandpass, 460 - 495 nm; dichromatic mirror, 505 nm; and emission bandpass, 510 - 550 nm) and 20X Plan-Apochromat lenses, 0.75 numerical aperture.</li>
</ol>

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O., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Integrated+&#946;-catenin,+BMP,+PTEN,+and+Notch+signalling+patterns+the+nephron.">Integrated &#946;-catenin, BMP, PTEN, and Notch signalling patterns the nephron.</a> eLife. 4, e04000 (2015).</li><li>Peuckert, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Multimodal+Eph/Ephrin+signaling+controls+several+phases+of+urogenital+development.">Multimodal Eph/Ephrin signaling controls several phases of urogenital development.</a> Kidney Int. 90 (2), 373-388 (2016).</li><li>Pasquale, E. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Eph+receptor+signalling+casts+a+wide+net+on+cell+behaviour.">Eph receptor signalling casts a wide net on cell behaviour.</a> Nat Rev Mol Cell Biol. 6 (6), 462-475 (2005).</li><li>Bonanomi, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Ret+Is+a+Multifunctional+Coreceptor+that+Integrates+Diffusible-+and+Contact-Axon+Guidance+Signals.">Ret Is a Multifunctional Coreceptor that Integrates Diffusible- and Contact-Axon Guidance Signals.</a> Cell. 148 (2), 568-582 (2012).</li><li>Brown, A. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+Culture+of+Cells+from+the+Nephrogenic+Zone+of+the+Embryonic+Mouse+Kidney.">Isolation and Culture of Cells from the Nephrogenic Zone of the Embryonic Mouse Kidney.</a> J Vis Exp. (50), e2555 (2011).</li><li>Grobstein, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inductive+interaction+in+the+development+of+the+mouse+metanephros.">Inductive interaction in the development of the mouse metanephros.</a> J Exp Zool. 130, 319-340 (1955).</li><li>Sax&#233;n, L., Toivonen, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=.">.</a> Primary Embryonic Induction. , (1962).</li><li>Sax&#233;n, L., Koskimies, O., Lahti, A., Miettinen, H., Rapola, J., Wartiovaara, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differentiation+of+kidney+mesenchyme+in+an+experimental+model+system.">Differentiation of kidney mesenchyme in an experimental model system.</a> Adv Morphog. 7, 251-293 (1968).</li><li>Dudley, A. T., Godin, R. E., Robertson, E. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interaction+between+FGF+and+BMP+signaling+pathways+regulates+development+of+metanephric+mesenchyme.">Interaction between FGF and BMP signaling pathways regulates development of metanephric mesenchyme.</a> Genes Dev. 13, 1601-1613 (1999).</li><li>Per&#228;l&#228;, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Sema4C-Plexin+B2+signalling+modulates+ureteric+branching+in+developing+kidney.">Sema4C-Plexin B2 signalling modulates ureteric branching in developing kidney.</a> Differentiation. 81 (2), 81-91 (2011).</li><li>Thesleff, I., Ekblom, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+transferrin+in+branching+morphogenesis,+growth+and+differentiation+of+the+embryonic+kidney.">Role of transferrin in branching morphogenesis, growth and differentiation of the embryonic kidney.</a> J Embryol exp Morph. 82, 147-161 (1984).</li><li>Watanabe, T., Costantini, F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Real-time+analysis+of+ureteric+bud+branching+morphogenesis.">Real-time analysis of ureteric bud branching morphogenesis.</a> Dev Biol. 271, 98-108 (2004).</li><li>Sebinger, D. D. R., Unbekandt, M., Ganeva, V. V., Ofenbauer, A., Werner, C., Davies, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Novel,+Low-Volume+Method+for+Organ+Culture+of+Embryonic+Kidneys+That+Allows+Development+of+Cortico-Medullary+Anatomical+Organization.">A Novel, Low-Volume Method for Organ Culture of Embryonic Kidneys That Allows Development of Cortico-Medullary Anatomical Organization.</a> PLoS One. 5 (5), e10550 (2010).</li><li>Ekblom, P., Miettinen, A., Virtanen, I., Wahlstr&#246;m, T., Dawnay, A., Sax&#233;n, L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=In+vitro+segregation+of+the+metanephric+nephron.">In vitro segregation of the metanephric nephron.</a> Dev Biol. 84 (1), 88-95 (1981).</li><li>Davies, J. A., Unbekandt, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=siRNA-mediated+RNA+interference+in+embryonic+kidney+organ+culture.">siRNA-mediated RNA interference in embryonic kidney organ culture.</a> Methods Mol Biol. 886, 295-303 (2012).</li><li>Sax&#233;n, L., Lehtonen, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Embryonic+kidney+in+organ+culture.">Embryonic kidney in organ culture.</a> Differentiation. 36 (1), 2-11 (1987).</li><li>Bard, J. B. 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+development+of+the+mouse+kidney+embryogenesis+writ+small.">The development of the mouse kidney embryogenesis writ small.</a> Curr Opin Genet Dev. 2, 589-595 (1992).</li><li>Davies, J. 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The authors have nothing to disclose.

This manuscript describes a method to isolate the developing metanephric anlagen from the mouse embryo and to culture the organ rudiments. This method is a standard technique, as developed by Grobstein8 and Sax&#233;n9,10, and was adapted and modified by many others11,12. The success of the method depends mainly on the duration of the dissection, as explant survival and inductive p...

The mammalian kidney is derived from two primordial structures with mesodermal origin: the tubular epithelial ureteric bud and the metanephric mesenchyme. During nephrogenesis, the ureteric bud invades the metanephric mesenchyme and branches to form the collecting system. The metanephric mesenchyme gives rise to the epithelial elements of the nephrons. These processes occur in a precisely timed and spatially coordinated manner and are initiated by reciprocal inductive mechanisms. Both tissue components communicate and affect the other's cell morphogenesis. 
In the 1920s, it was Boyden who performed the in vivo obstruction of the mesonephric duct in chicken, providing the first indication of inductive interactions as separated nephric blastema fail to differentiate1. At about the same time, the first successful attempts to culture chicken nephric rudiments in a hanging drop were published. Subsequently, the organ culture was developed to study tissue interactions in mammalian organogenesis. In the 1950s, Grobstein developed a technique in which metanephric rudiments could be cultured on a filter. This technique was modified by Sax&#233;n, who placed the filter on a Trowell-type screen in a culture dish1. Over the years, many modifications and applications for organ culture have emerged. The method described here is based on Sax&#233;n's technique but is simplified, as the filters float free on the medium and the diameter of the culture well only slightly exceeds the diameter of the filter, limiting unwanted movement of the filter.
Whole-organ culture is a classical, cheap, and simple but powerful tool to investigate cellular processes and intercellular communication during organogenesis. Organ culture allows for treatment with biological agents, such as growth factors, antibodies, antisense oligonucleotides, viruses, and peptides, as well as with pharmaceutical compounds and other chemicals. Also, gene function may be studied using explants derived from genetically modified mice or using inducible gene inactivation technology, such as the Cre-loxP system. This allows for the study of genetic mutations that cause embryonic lethality prior to the development of the kidney. Organ culture can also be combined with fluorescent tagging for gene function or lineage tracing and modern imaging techniques, which enable real-time monitoring of cell behavior2.
In the specific example provided here, the effect of EphrinB2-activated Eph-receptor signaling on the branching morphology of the ureteric bud was investigated. The morphology of the EphA4/EphB2 double-knockout mice suggested several severe defects in kidney development, which were detectable as early as embryonic day 11 (E11) and involved the ureteric bud, the ureter, and the common nephric duct3. Signaling via Eph receptors requires the clustering of the ligand-receptor dimer4. To over-activate Eph signaling, the kidney rudiments from E11.5 mouse embryos were cultured in the presence of clustered recombinant EphrinB2-Fc. EphrinB2 is a known ligand for the EphA4 receptor, which is expressed in the ureteric bud tips3.

<table><tbody><tr><td>DMEM/F-12</td><td>Thermo Fisher Scientific</td><td>21331020</td><td></td></tr><tr><td>Penicillin-Streptomycin (10,000 U/mL)</td><td>Thermo Fisher Scientific</td><td>15140148</td><td></td></tr><tr><td>GlutaMAX Supplement</td><td>Thermo Fisher Scientific</td><td>35050061</td><td></td></tr><tr><td>DPBS, calcium, magnesium</td><td>Thermo Fisher Scientific</td><td>14040117</td><td>use for dissection</td></tr><tr><td>holo-Transferrin human</td><td>Sigma-Aldrich</td><td>T0665</td><td></td></tr><tr><td>Insulin-Transferrin-Selenium (ITS -G) (100x)</td><td>Thermo Fisher Scientific</td><td>41400045</td><td></td></tr><tr><td>Paraformaldehyde</td><td>Sigma-Aldrich</td><td>158127</td><td></td></tr><tr><td>Amphotericin B solution</td><td>Sigma-Aldrich</td><td>A2942</td><td></td></tr><tr><td>Triton X-100</td><td>Sigma-Aldrich</td><td>X100</td><td></td></tr><tr><td>Sodium azide</td><td>Sigma-Aldrich</td><td>S8032</td><td></td></tr><tr><td>Thimerosal</td><td>Sigma-Aldrich</td><td>T5125</td><td></td></tr><tr><td>Propyl gallate</td><td>Sigma-Aldrich</td><td>2370</td><td></td></tr><tr><td>Mowiol 4-88</td><td>Sigma-Aldrich</td><td>81381</td><td></td></tr><tr><td>Glycerol</td><td>Sigma-Aldrich</td><td>G5516</td><td></td></tr><tr><td>Biotinylated Dolichorus Biflorus Agglutinin</td><td>Vector Laboratories</td><td>B-1035</td><td></td></tr><tr><td>Alexa488 conjugated Streptavidin</td><td>Jackson Immuno Research</td><td>016-540-084</td><td></td></tr><tr><td>Recombinant Mouse Ephrin-B2 Fc Chimera Protein, CF</td><td>R&amp;amp;D Systems</td><td>496-EB</td><td></td></tr><tr><td>Recombinant Human IgG1 Fc, CF</td><td>R&amp;amp;D Systems</td><td>110-HG-100</td><td></td></tr><tr><td>Goat Anti-Human IgG Fc Antibody</td><td>R&amp;amp;D Systems</td><td>G-102-C</td><td></td></tr><tr><td>Phosphate buffered saline tablets</td><td>Sigma-Aldrich</td><td>P4417</td><td>use for fixation and immunostaining</td></tr><tr><td>Dumont #5, biologie&lt;br/&gt; tips, INOX, 11 cm</td><td>agnthos.se</td><td>0208-5-PS</td><td>2 pairs of forceps are needed</td></tr><tr><td>Iris scissors, straight, 12 cm</td><td>agnthos.se</td><td>03-320-120</td><td></td></tr><tr><td>Dressing Forceps,&lt;br/&gt; straight, delicate, 13 cm</td><td>agnthos.se</td><td>08-032-130</td><td></td></tr><tr><td>Petri dishes Nunclo Delta treated</td><td>Thermo Fisher Scientific</td><td>150679</td><td></td></tr><tr><td>TMTP01300 Isopore Membrane Filter, polycarbonate, Hydrophilic, 5.0 &amp;micro;m, 13 mm, white, plain</td><td>MerckMillipore</td><td>TMTP01300</td><td></td></tr><tr><td>Nunclon Multidishes&lt;br/&gt; 4 wells, flat bottom</td><td>Sigma-Aldrich</td><td>D6789-1CS</td><td></td></tr><tr><td>Microscope cover glass 24 x 50 mm thickn. No.1.5H 0.17+/-0.005 mm</td><td>nordicbiolabs</td><td>107222</td><td></td></tr><tr><td>Cover glasses No.1.5, 18 mm x 18 mm</td><td>nordicbiolabs</td><td>102032</td><td></td></tr><tr><td>Slides ~76 x 26 x 1, 1/2-w. ground plain</td><td>nordicbiolabs</td><td>1030418</td><td></td></tr><tr><td>VWR Razor Blades</td><td>VWR</td><td>55411-055</td><td></td></tr><tr><td>50 mL centrifuge tubes</td><td>Sigma-Aldrich</td><td>CLS430828</td><td></td></tr><tr><td>15 mL centrifuge tubes</td><td>Sigma-Aldrich</td><td>CLS430055</td><td></td></tr><tr><td>Whatman prepleated qualitative filter paper, Grade 113V, creped</td><td>Sigma-Aldrich</td><td>WHA1213125</td><td></td></tr><tr><td>Fixed stage research mircoscope</td><td>Olympus</td><td>BX61WI</td><td></td></tr><tr><td>Black 6 inbred mice, male, C57BL/6NTac</td><td>Taconic</td><td>B6-M</td><td></td></tr><tr><td>Black 6 inbred mice,female, C57BL/6NTac</td><td>Taconic</td><td>B6-F</td><td></td></tr><tr><td>Greenough Stereo Microscope</td><td>Leica</td><td>Leica S6 E</td><td></td></tr></tbody></table>

dissection and culture of mouse embryonic kidney

The goal of this protocol is to describe a method for the dissection, isolation, and culture of mouse metanephric rudiments. 
During mammalian kidney development, the two progenitor tissues, the ureteric bud and the metanephric mesenchyme, communicate and reciprocally induce cellular mechanisms to eventually form the collecting system and the nephrons of the kidney. As mammalian embryos grow intrauterine and therefore are inaccessible to the observer, an organ culture has been developed. With this method, it is possible to study epithelial-mesenchymal interactions and cellular behavior during kidney organogenesis. Furthermore, the origin of congenital kidney and urogenital tract malformations can be investigated. After careful dissection, the metanephric rudiments are transferred onto a filter that floats on culture medium and can be kept in a cell culture incubator for several days. However, one must be aware that the conditions are artificial and could influence the metabolism in the tissue. Also, the penetration of test substances could be limited due to the extracellular matrix and basal membrane present in the explant.
One main advantage of organ culture is that the experimenter can gain direct access to the organ. This technology is cheap, simple, and allows a large number of modifications, such as the addition of biologically active substances, the study of genetic variants, and the application of advanced imaging techniques.

Metanephric kidney anlagen were derived from pregnant Black-6 inbred mice at E11.5 and were cultured. After 3 days, the ureteric bud had branched up to 5 times, resulting in a ramification of the initially T-shaped ureteric bud. Each explant was photographed, and the numbers of segments and endpoints were quantified to determine the branching generations and to calculate the number of endpoints per branch (Figure 1). ImageJ (rd generation; the 4th ge...

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Dissection and Culture of Mouse Embryonic Kidney

This protocol describes a method for isolating and culturing metanephric rudiments from mouse embryos.

The goal of this protocol is to describe a method for the dissection, isolation, and culture of mouse metanephric rudiments. 
During mammalian kidney ...

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Research

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Developmental Biology

11.9K Views.  Uppsala University. This protocol describes a method for isolating and culturing metanephric rudiments from mouse embryos.

Video: Dissection and Culture of Mouse Embryonic Kidney

Neural Tube Closure in Mouse Whole Embryo Culture

Genetic mouse models are an important tool in the study of mammalian neural tube closure (Gray &amp; Ross, 2009; Ross, 2010). However, the study of mouse embryos in utero is limited by our inability to directly pharmacologically manipulate the embryos in isolation from the effects of maternal metabolism on the reagent of interest. Whether using a small molecule, recombinant protein, or siRNA, delivery of these substances to the mother, through the diet or by injection will subject these unstable compounds to a variety of bodily defenses that could prevent them from reaching the embryo. Investigations in cultures of whole embryos can be used to separate maternal from intrinsic fetal effects on development.
Here, we present a method for culturing mouse embryos using highly enriched media in a roller incubator apparatus that allows for normal neural tube closure after dissection (Crockett, 1990). Once in culture, embryos can be manipulated using conventional in vitro techniques that would not otherwise be possible if the embryos were still in utero. Embryo siblings can be collected at various time points to study different aspects of neurulation, occurring from E7-7.5 (neural plate formation, just prior to the initiation of neurulation) to E9.5-10 (at the conclusion of cranial fold and caudal neuropore closure, Kaufman, 1992). In this protocol, we demonstrate our method for dissecting embryos at timepoints that are optimal for the study of cranial neurulation. Embryos will be dissected at E8.5 (approx. 10-12 somities), after the initiation of neural tube closure but prior to embryo turning and cranial neural fold closure, and maintained in culture till E10 (26-28 somities), when cranial neurulation should be complete.

A method allowing for direct pharmacological manipulation of mouse embryos during neurulation that bypasses maternal metabolism is described. The technique can be adapted to study different aspects of neurulation by varying the time point and pharmacological agent.

Genetic mouse models are an important tool in the study of mammalian neural tube closure (Gray &amp; Ross, 2009; Ross, 2010).  However, the study of mouse ...

Neuroscience

Organ Culture and Whole Mount Immunofluorescence Staining of Mouse Wolffian Ducts

Tubal morphogenesis is a fundamental requirement for the development of most mammalian organs, including the male reproductive system. The epididymis, an integral part of the male reproductive tract, is responsible for sperm storage, maturation, and transport. The adult epididymis is a highly coiled tube that develops from a simple and straight embryonic precursor known as Wolffian duct (WD). Proper coiling of the epididymis is essential for male fertility, as sperm in the testis are unable to fertilize an oocyte. However, the mechanism responsible for epididymal development and coiling remains unclear, partially due to the lack of whole organ culture and imaging methods. In this study, we describe an in vitro culture system and whole mount immunofluorescence protocol to better visualize the process of WD coiling and development, which may also be applied to study other tubular organs.

We present a method for isolation and culture of the mouse Wolffian duct (WD). We also demonstrate a detailed procedure for whole mount immunostaining of cultured/freshly isolated WDs with fluorescently tagged antibodies. Together, these techniques enable the study of WD development, coiling, and differentiation.

Tubal morphogenesis is a fundamental requirement for the development of most mammalian organs, including the male reproductive system. The epididymis, an ...

Optimization of Renal Organoid and Organotypic Culture for Vascularization, Extended Development, and Improved Microscopy Imaging

Embryonic kidney organotypic cultures, and especially pluripotent stem cell-derived kidney organoids, are excellent tools for following developmental processes and modelling kidney disease. However, the models are limited by a lack of vascularization and functionality. To address this, an improved protocol for the method of xenografting cells and tissues to the chorioallantoic membrane (CAM) of an avian embryo to gain vascularization and restoration of blood flow was developed. The grafts are overlaid with custom-made minireservoirs that fix the samples to the CAM and supply them with culture medium that protects the grafts from drying. The improved culture method allows xenografts to grow for up to 9 days. The manuscript also describes how to provide optimal conditions for long-term confocal imaging of renal organoids and organotypic cultures using the previously published Fixed Z-Direction (FiZD) method. This method gently compresses an embryonic organ or organoid between a glass coverslip and membrane in a large amount of medium and provides excellent conditions for imaging for up to 12 days. Together, these methods allow vascularization and blood flow to renal organoids and organotypic kidney cultures with improved confocal imaging. The methods described here are highly beneficial for studying fundamental and applied functions of kidneys ex vivo. Both methods are applicable to various types of tissues and organoids.

This work describes two methods for studying organ development, an improved xenotransplantation setup on chorioallantoic membrane (CAM) from avian embryos that allows for vascularization of cultured embryonic organs and organoids and a novel fixed z-direction organ culture method with modified experimental conditions that allows for high-resolution time-lapse confocal imaging.

Embryonic kidney organotypic cultures, and especially pluripotent stem cell-derived kidney organoids, are excellent tools for following developmental ...

Mouse Embryonic Lung Culture, A System to Evaluate the Molecular Mechanisms of Branching

Lung primordial specification as well as branching morphogenesis, and the formation of various pulmonary cell lineages requires a specific interaction of the lung endoderm with its surrounding mesenchyme and mesothelium. Lung mesenchyme has been shown to be the source of inductive signals for lung branching morphogenesis. Epithelial-mesenchymal-mesothelial interactions are also critical to embryonic lung morphogenesis. Early embryonic lung organ culture is a very useful system to study epithelial-mesenchymal interactions. Both epithelial and mesenchymal morphogenesis proceeds under specific conditions that can be readily manipulated in this system (in the absence of maternal influence and blood flow). More importantly this technique can be readily done in a serumless, chemically defined culture media. Gain and loss of function can be achieved using expressed proteins, recombinant viral vectors and/or analysis of transgenic mouse strains, antisense RNA, as well as RNA interference gene knockdown.

Early embryonic lung organ culture is a very useful system to study epithelial-mesenchymal interactions. Both epithelial and mesenchymal morphogenesis proceeds under specific conditions that can be readily manipulated in this system.

Lung primordial specification as well as branching morphogenesis, and the formation of various pulmonary cell lineages requires a specific interaction of ...

Biology

Microdissection of Primary Renal Tissue Segments and Incorporation with Novel Scaffold-free Construct Technology

Kidney transplantation is now a mainstream therapy for end-stage renal disease. However, with approximately 96,000 people on the waiting list and only one-fourth of these patients achieving transplantation, there is a dire need for alternatives for those with failing organs. In order to decrease the harmful consequences of dialysis along with the overall healthcare costs it incurs, active investigation is ongoing in search of alternative solutions to organ transplantation. Implantable tissue-engineered renal cellular constructs are one such feasible approach to replacing lost renal functionality. Here, described for the first time, is the microdissection of murine kidneys for isolation of living corticomedullary renal segments. These segments are capable of rapid incorporation within scaffold-free endothelial-fibroblast constructs which may enable rapid connection with host vasculature once implanted. Adult mouse kidneys were procured from living donors, followed by stereoscope microdissection to obtain renal segments 200 - 300 &#181;m in diameter. Multiple renal constructs were fabricated using primary renal segments harvested from only one kidney. This method demonstrates a procedure which could salvage functional renal tissue from organs that would otherwise be discarded.

Tissue-engineered renal constructs provide a solution for the organ shortage and deleterious effects of dialysis. Here, we describe a protocol to micro dissect murine kidneys for isolation of cortico-medullary segments. These segments are implanted into scaffold-free cellular constructs, forming renal organoids.

Kidney transplantation is now a mainstream therapy for end-stage renal disease. However, with approximately 96,000 people on the waiting list and only ...

Bioengineering

Isolation and Culture of Cells from the Nephrogenic Zone of the Embryonic Mouse Kidney

Embryonic development of the kidney has been extensively studied both as a model for epithelial-mesenchymal interaction in organogenesis and to gain understanding of the origins of congenital kidney disease. More recently, the possibility of steering na&iuml;ve embryonic stem cells toward nephrogenic fates has been explored in the emerging field of regenerative medicine. Genetic studies in the mouse have identified several pathways required for kidney development, and a global catalog of gene transcription in the organ has recently been generated <a href="http://www.gudmap.org/">http://www.gudmap.org/</a>, providing numerous candidate regulators of essential developmental functions. Organogenesis of the rodent kidney can be studied in organ culture, and many reports have used this approach to analyze outcomes of either applying candidate proteins or knocking down the expression of candidate genes using siRNA or morpholinos. However, the applicability of organ culture to the study of signaling that regulates stem/progenitor cell differentiation versus renewal in the developing kidney is limited as cultured organs contain a compact extracellular matrix limiting diffusion of macromolecules and virus particles. To study the cell signaling events that influence the stem/progenitor cell niche in the kidney we have developed a primary cell system that establishes the nephrogenic zone or progenitor cell niche of the developing kidney ex vivo in isolation from the epithelial inducer of differentiation. Using limited enzymatic digestion, nephrogenic zone cells can be selectively liberated from developing kidneys at E17.5. Following filtration, these cells can be cultured as an irregular monolayer using optimized conditions. Marker gene analysis demonstrates that these cultures contain a distribution of cell types characteristic of the nephrogenic zone in vivo, and that they maintain appropriate marker gene expression during the culture period. These cells are highly accessible to small molecule and recombinant protein treatment, and importantly also to viral transduction, which greatly facilitates the study of candidate stem/progenitor cell regulator effects. Basic cell biological parameters such as proliferation and cell death as well as changes in expression of molecular markers characteristic of nephron stem/progenitor cells in vivo can be successfully used as experimental outcomes. Ongoing work in our laboratory using this novel primary cell technique aims to uncover basic mechanisms governing the regulation of self-renewal versus differentiation in nephron stem/progenitor cells.

In this report we describe a method for the isolation and culture of the progenitor cell niche from the embryonic mouse kidney that can be used to study signaling pathways regulating stem/progenitor cells of the developing kidney. These cultured cells are highly accessible to small molecule and recombinant protein treatment, and importantly also to viral transduction, which allows efficient manipulation of candidate pathways.

Embryonic development of the kidney has been extensively studied both as a model for epithelial-mesenchymal interaction in organogenesis and  to gain ...

Isolation and Culture of Embryonic Mouse Neural Stem Cells

Neural stem cells (NSCs) are multipotent and can give rise to the three major cell types of the central nervous system (CNS). In vitro culture and expansion of NSCs provide a suitable source of cells for neuroscientists to study the function of neurons and glial cells along with their interactions. There are several reported techniques for the isolation of neural stem cells from adult or embryo mammalian brains. During the microsurgical operation to isolate NSCs from different regions of the embryonic CNS, it is very important to reduce the damage to the brain cells to obtain the highest ratio of live and expandable stem cells. A possible technique for stress reduction during isolation of these cells from the mouse embryo brain is the reduction of surgical time. Here, we demonstrate a developed technique for rapid isolation of these cells from the E13 mouse embryo ganglionic eminence. Surgical procedures include harvesting E13 mouse embryos from the uterus, cutting the frontal fontanelle of the embryo with a bent needle tip, extracting the brain from the skull, microdissection of the isolated brain to harvest the ganglionic eminence, dissociation of the harvested tissue in NSC medium to gain a single cell suspension, and finally plating cells in suspension culture to generate neurospheres.

Here, we introduce a novel microsurgical technique for the isolation of neural stem cells from the E13 mouse embryo ganglionic eminence.

Neural stem cells (NSCs) are multipotent and can give rise to the three major cell types of the central nervous system (CNS). In vitro culture and ...

Mouse Embryonic Development in a Serum-free Whole Embryo Culture System

Mid-gestation stage mouse embryos were cultured utilizing a serum-free culture medium prepared from commercially available stem cell media supplements in an oxygenated rolling bottle culture system. Mouse embryos at E10.5 were carefully isolated from the uterus with intact yolk sac and in a process involving precise surgical maneuver the embryos were gently exteriorized from the yolk sac while maintaining the vascular continuity of the embryo with the yolk sac. Compared to embryos prepared with intact yolk sac or with the yolk sac removed, these embryos exhibited superior survival rate and developmental progression when cultured under similar conditions. We show that these mouse embryos, when cultured in a defined medium in an atmosphere of 95% O2 / 5% CO2 in a rolling bottle culture apparatus at 37 &#176;&#8203;C for 16-40 hr, exhibit morphological growth and development comparable to the embryos developing in utero. We believe this method will be useful for investigators needing to utilize whole embryo culture to study signaling interactions important in embryonic organogenesis.

Serum utilized in embryo cultures contains unknown components that can affect the outcome of experiments especially in studies involving signaling interactions. Here we utilized a serum-free oxygenated culture system and show that mid-gestation mouse embryos cultured for 16-40 hr&#160;exhibit morphological development comparable to embryos developing in utero.

Mid-gestation stage mouse embryos were cultured utilizing a serum-free culture medium prepared from commercially available stem cell media supplements in ...

Glomerular Outgrowth as an Ex Vivo Assay to Analyze Pathways Involved in Parietal Epithelial Cell Activation

Parietal epithelial cell (PEC) activation is one of the key factors involved in the development and progression of glomerulosclerosis. Inhibition of pathways involved in parietal epithelial cell activation could therefore be a tool to attenuate the progression of glomerular diseases. This article describes a method to culture and analyze parietal epithelial cell outgrowth of encapsulated glomeruli isolated from mouse kidney. After dissecting isolated mouse kidneys, the tissue is minced, and glomeruli are isolated by sieving. Encapsulated glomeruli are collected, and single glomeruli are cultured for 6 days to obtain glomerular outgrowth of parietal epithelial cells. During this period, parietal epithelial cell proliferation and migration can be analyzed by determining the cell number or the surface area of outgrowing cells. This assay can therefore be used as a tool to study the effects of an altered gene expression in transgenic- or knockout-mice or the effects of culture conditions on parietal epithelial cell growth characteristics and signaling. Using this method, important pathways involved in the process of parietal epithelial cell activation and consequently in glomerulosclerosis can be studied.

This article describes a method for culturing and analyzing glomerular parietal epithelial cell outgrowths of encapsulated glomeruli isolated from mouse kidney. This method can be used to study pathways involved in parietal epithelial cell proliferation and migration.

Parietal epithelial cell (PEC) activation is one of the key factors involved in the development and progression of glomerulosclerosis. Inhibition of ...

Efficient Dissection and Culture of Primary Mouse Retinal Pigment Epithelial Cells

Eye disorders affect millions of people worldwide, but the limited availability of human tissues hinders their study. Mouse models are powerful tools to understand the pathophysiology of ocular diseases because of their similarities with human anatomy and physiology. Alterations in the retinal pigment epithelium (RPE), including changes in morphology and function, are common features shared by many ocular disorders. However, successful isolation and culture of primary mouse RPE cells is very challenging. This paper is an updated audiovisual version of the protocol previously published by Fernandez-Godino et al. in 2016 to efficiently isolate and culture primary mouse RPE cells. This method is highly reproducible and results in robust cultures of highly polarized and pigmented RPE monolayers that can be maintained for several weeks on Transwells. This model opens new avenues for the study of the molecular and cellular mechanisms underlying eye diseases. Moreover, it provides a platform to test therapeutic approaches that can be used to treat important eye diseases with unmet medical needs, including inherited retinal disorders and macular degenerations.

This protocol, which was originally reported by Fernandez-Godino et al. in 20161, describes a method to efficiently isolate and culture mouse RPE cells, which form a functional and polarized RPE monolayer within one week on Transwell plates. The procedure takes approximately 3 hours.

Eye disorders affect millions of people worldwide, but the limited availability of human tissues hinders their study. Mouse models are powerful tools to ...