The authors would like to acknowledge Dr. Robert Price and the staff of the Instrumentation Resource Facility at the University of South Carolina School of Medicine. This work was partially supported by a SPARC Graduate Research Grant from the Office of the Vice President for Research at the University of South Carolina (JDP/VM). In addition this work was supported by Cook Biotech research agreement (JDP) and by FirstString Research Inc (JDP) and NIH 2 P20-RR016434-06 (JDP). In addition, NIH IDeA Networks of Biomedical Research Excellence (INBRE) grant for South Carolina P20GM103499 (JE)

Avian embryos are not considered vertebrate animals under IUCAC regulations.
1. Obtaining Embryos for Surgery
<ol>
	<li>Incubate 80 - 90 fertilized Bovan chicken eggs (blunt end up) in a humidified (60%) rocker incubator at 40 &#176;C for approximately 72 hr to obtain embryos at Hamilton and Hamburger (HH) stage 17. Determine exact number of eggs based on power analysis and survival rate of embryos 17. Use plastic egg trays for incubation to allow adequate air circulation.</li>
	<li>Once this desired developmental stage is attained, pour approximately 20 ml of warm (37 &#176;C) Tyrode&#39;s buffer (supplemented with sodium bicarbonate (1 g/L)) into a 100 mm x 26 mm petri dish.</li>
	<li>Sterilize an egg shell with 70% ethanol.</li>
	<li>Gently crack the shell with a scalpel handle and carefully release its contents into the dish containing Tyrode&#39;s buffer. Discard embryos if (i) they visually appear abnormal (ii) they are not at the right developmental stage (iii) they are improperly oriented on the yolk and/or (iv) any bleeding occurs. Retain any embryos not subjected to surgery immediately after being placed ex ovo at 40 &#176;C so as to not compromise development. 
	Note: Staging is performed based on Hamilton and Hamburger 18. Abnormality of chick embryos is determined by the naked eye and under the dissection scope. Ensure that the embryo has appropriate folding and bending and vasculature.</li>
</ol>
2. OFT Banding
<ol>
	<li>Tweeze out individual 1 cm long threads from a single 11/0 nylon surgical suture and form a loose knot. UV sterilize all preformed knots.</li>
	<li>Under a dissection microscope, visually ensure that the heart is beating at a normal rate (~ 120 beats/min). If not, discard the embryo.</li>
	<li>Just before surgery, apply 5 - 6 ml of warm (37 &#176;C) Tyrode&#39;s buffer to the embryo surface using a transfer pipette.</li>
	<li>Pass one free end of the preformed knot under the OFT, position the suture at the OFT/ventricle junction (OVJ) (or desired location), and pass the free end into the knot thereby constricting the OFT including the membranes surrounding the heart.</li>
	<li>After surgery, wet the surface of the yolk with 5 - 6 ml of warm (37 &#176;C) Tyrode&#39;s buffer using a transfer pipette.</li>
	<li>Maintain control embryos ex ovo as the banded embryos; however do not subject them to the surgical procedure.</li>
	<li>Incubate the embryos, for the desired amount of time, at 40 &#176;C in a humidified (60%) incubator.</li>
	<li>Once the desired time point is reached, excise the embryo from the yolk using straight scissors. Dissect the heart with fine forceps and use for several downstream studies such as changes in cardiac morphology due to altered hemodynamics 17.</li>
</ol>
3. Confirming that the Banding Intervention Causes a Change in Hemodynamics
Note: The partial constriction caused by the banding intervention leads to an increase in blood flow velocity at the OVJ. This hemodynamic parameter is conveniently assessed using 2D ultrasound imaging, which is performed at the desired time point of the experiment.
<ol>
	<li>Since only a single embryo can be imaged at a time, maintain all other embryos designated for ultrasound imaging in a 40 &#176;C incubator.</li>
	<li>Place the petri dish containing the embryo to be imaged on a heating pad set at 40 &#176;C.</li>
	<li>Fill the dish, up to the brim, with warm (37 &#176;C) Tyrode&#39;s buffer. Slowly pour the buffer solution into the dish so as to keep the yolk intact. If, however, the integrity of the yolk is compromised during this step, discard the embryo.</li>
	<li>Orient the embryo such that the central axis of the embryo is perpendicular to the ultrasound probe which is suspended from an adjustable stand.</li>
	<li>With the ultrasound machine operating in B-mode, obtain a 2D image of the beating heart on the screen and move the stage (heating pad) such that the OFT, ventricle and OVJ are clearly visible.</li>
	<li>Switch to the pulsed-wave (PW) mode, at the desired pulse repetition frequency (e.g., 20 kHz) and obtain velocity data exactly at the OVJ. A B-mode image of the beating heart is obtained on the screen.
	<ol>
		<li>Move the stage to see the OFT, ventricle and the OVJ. Using the ultrasound machine software, obtain velocity measurements exactly at the OVJ.</li>
	</ol>
	</li>
</ol>
Note: If the heart rate of an embryo decreases during imaging, velocity data thus obtained should not be used for analysis. All embryos used for velocity measurements should preferably not be used for any other experiments after ultrasound imaging.

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The authors have nothing to disclose.

This technique is relatively quick and easy to perform, however certain key points need to be kept in mind so as to get accurate downstream results. Embryos should be maintained ex ovo in a petri dish that contains Tyrode&#39;s buffer to provide adequate rehydration. It is also important to hydrate the yolk post-surgery with Tyrode&#39;s buffer and to make sure the incubation chamber is adequately hydrated. Surgeries should not be performed on an embryo if any bleeding is visible or the yolk is even slightly bro...

Abnormally formed outflow valves are the most common type of congenital heart defects 1. However, defective cardiac valve structure and function, even though present at birth, may become symptomatic only in adulthood. In fact, several adult valve diseases can be attributed to a congenital origin. Treatment of such patients often involves replacing defective valves, and, importantly, replaced aortic valves have been shown to have congenital anomalies 2. Given the fact that critical processes involved in valve development begin early during embryogenesis, the importance of better understanding the mechanisms that regulate these events is highlighted. 
The primitive heart tube, which is the first functioning organ in an embryo, exhibits two distinct layers - an endothelial endocardium surrounded by myocardium - separated by extracellular matrix (cardiac jelly) which is mostly produced and secreted by the myocardium 3-5. As development continues, valve primordia (endocardial cushions) are formed, after rightward looping of the embryonic heart, by local expansion of the cardiac jelly at the atrioventricular (AV) canal and the outflow tract (OFT) 4,6. This expansion is mediated by the highly regulated process of epithelial-mesenchymal transition (EMT), during which the cardiac jelly becomes populated by endocardially-derived mesenchymal cells 6. In addition to the mesenchymal population derived through EMT, neural crest cells are also involved in valvulogenesis of the OFT 3. 
Hemodynamic stimuli, such as shear stress, are important epigenetic factors that regulate heart development in the embryo 7,8. Using a 3D in vitro system, we have previously shown shear stress to be a factor influencing the expression and deposition of fibrous extracellular matrix (ECM) proteins in AV and OFT cushions 9,10. Moreover, studies carried out by several researchers have demonstrated that altered blood flow leads to improper valves and septa formation 11-16. Recently, using the novel banding procedure presented here, we have shown that changing hemodynamics in the embryonic chick heart affects the early processes involved in OFT valve formation 17.
The technique described here provides a novel model for altering hemodynamics in the developing chick heart by partially constricting the OFT ex ovo. This reproducible procedure is relatively quick and allows researchers to obtain a sufficient number of embryos/whole hearts/OFT tissue, etc. for downstream analyses including gene expression studies. Moreover, this new model can be used to study 'chronic' effects of altered hemodynamics on OFT valve development.

<table border="0" cellpadding="0" cellspacing="0" width="600">
	<tbody>
		<tr height="105">
			<td height="105" style="height:105px;width:216px;">Fertilized Bovan chicken eggs</td>
			<td style="width:71px;">Clemson University, Clemson, SC</td>
			<td style="width:119px;"></td>
			<td style="width:195px;"></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">11/0 Nylon suture</td>
			<td style="width:71px;">Ashaway</td>
			<td style="width:119px;">S30001</td>
			<td>UV sterilize knots before surgery</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">100 x 26 mm petri dish</td>
			<td style="width:71px;">VWR</td>
			<td style="width:119px;">25387-030</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Transfer pipettes</td>
			<td style="width:71px;">Thermo Scientific&#160;</td>
			<td style="width:119px;">232-20S</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Scalpel handle #3</td>
			<td style="width:71px;">Fine Science Tools</td>
			<td style="width:119px;">91003-12</td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:216px;">Straight scissor</td>
			<td style="width:71px;">Roboz</td>
			<td style="width:119px;">RS-6702</td>
			<td></td>
		</tr>
		<tr height="63">
			<td height="63" style="height:63px;width:216px;">Dumont #5 fine forceps</td>
			<td style="width:71px;">Fine Science Tools</td>
			<td style="width:119px;">11254-20</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Tyrodes buffer</td>
			<td style="width:71px;">Sigma-Aldrich</td>
			<td style="width:119px;">2145-10L</td>
			<td>Filter sterlize before use&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Sodium bicarbonate</td>
			<td style="width:71px;">Fisher Scientific</td>
			<td style="width:119px;">S233-500</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">Vevo 770 Ultrasound Imaging system</td>
			<td style="width:71px;">VisualSonics, Inc.</td>
			<td style="width:119px;">VS-11392</td>
			<td></td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:216px;">708 Ultrasound transducer&#160;</td>
			<td style="width:71px;">VisualSonics, Inc.</td>
			<td style="width:119px;">VS-11171</td>
			<td></td>
		</tr>
	</tbody>
</table>

a novel ex ovo banding technique to alter intracardiac hemodynamics in an embryonic chicken system

The new model presented here can be used to understand the influence of hemodynamics on specific cardiac developmental processes, at the cellular and molecular level. To alter intracardiac hemodynamics, fertilized chicken eggs are incubated in a humidified chamber to obtain embryos of the desired stage (HH17). Once this developmental stage is achieved, the embryo is maintained ex ovo and hemodynamics in the embryonic heart are altered by partially constricting the outflow tract (OFT) with a surgical suture at the junction of the OFT and ventricle (OVJ). Control embryos are also cultured ex ovo but are not subjected to the surgical intervention. Banded and control embryos are then incubated in a humidified incubator for the desired period of time, after which 2D ultrasound is employed to analyze the change in blood flow velocity at the OVJ as a result of OFT banding. Once embryos are maintained ex ovo, it is important to ensure adequate hydration in the incubation chamber so as to prevent drying and eventually embryo death. Using this new banded model, it is now possible to perform analyses of changes in the expression of key players involved in valve development and to understand the role of hemodynamics on cellular responses in vivo, which could not be achieved previously.

Shown in Figure 1 are recommended instruments needed for OFT banding. The petri dish (Figure 1A) containing the embryo ex ovo should be deep enough so as to not destroy the embryo when covered with the lid. Deep petri dishes (Figure 1C) should also be used for ultrasound imaging to allow an adequate volume of Tyrode&#39;s buffer to be poured atop the yolk.
A single 1 cm...

Watch this Scientific Journal Video about A Novel Ex Ovo Banding Technique to Alter Intracardiac Hemodynamics in an Embryonic Chicken System at JoVE.com

A Novel Ex Ovo Banding Technique to Alter Intracardiac Hemodynamics in an Embryonic Chicken System

For the first time we present here a reproducible banding procedure to alter hemodynamics in the developing heart ex ovo. This is achieved by partially constricting the outflow tract (OFT).

A Novel Ex Ovo Banding Technique to Alter Intracardiac Hemodynamics in an Embryonic Chicken System

The new model presented here can be used to understand the influence of hemodynamics on specific cardiac developmental processes, at the cellular and ...

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6.5K Views.  School of Medicine, University of South Carolina. For the first time we present here a reproducible banding procedure to alter hemodynamics in the developing heart ex ovo. This is achieved by partially constricting the outflow tract (OFT). 

Video: A Novel Ex Ovo Banding Technique to Alter Intracardiac Hemodynamics in an Embryonic Chicken System

Efficient Gene Transfer in Chick Retinas for Primary Cell Culture Studies: An Ex-ovo Electroporation Approach

The cone photoreceptor-enriched cultures derived from embryonic chick retinas have become an indispensable tool for researchers around the world studying the biology of retinal neurons, particularly photoreceptors. The applications of this system go beyond basic research, as they can easily be adapted to high throughput technologies for drug development. However, genetic manipulation of retinal photoreceptors in these cultures has proven to be very challenging, posing an important limitation to the usefulness of the system. We have recently developed and validated an ex&#160;ovo plasmid electroporation technique that increases the rate of transfection of retinal cells in these cultures by five-fold compared to other currently available protocols1. In this method embryonic chick eyes are enucleated at stage 27, the RPE is removed, and the retinal cup is placed in a plasmid-containing solution and electroporated using easily constructed custom-made electrodes. The retinas are then dissociated and cultured using standard procedures. This technique can be applied to overexpression studies as well as to the downregulation of gene expression, for example via the use of plasmid-driven RNAi technology, commonly achieving transgene expression in 25% of the photoreceptor population. The video format of the present publication will make this technology easily accessible to researchers in the field, enabling the study of gene function in primary retinal cultures. We have also included detailed explanations of the critical steps of this procedure for a successful outcome and reproducibility.

Efficient Gene Transfer in Chick Retinas for Primary Cell Culture Studies: An Ex-ovo Electroporation Approach

Embryonic chick retinal cell cultures constitute valuable tools for the study of photoreceptor biology. We have developed an efficient gene transfer technique based on ex&#160;ovo plasmid electroporation of the retinas prior to culture. This technique considerably increases transfection efficiencies over currently available protocols, making genetic manipulation feasible for this system.

The cone photoreceptor-enriched cultures derived from embryonic chick retinas have become an indispensable tool for researchers around the world studying ...

Optimized Ex-ovo Culturing of Chick Embryos to Advanced Stages of Development

Research in anatomy, embryology, and developmental biology has largely relied on the use of model organisms. In order to study development in live embryos model organisms, such as the chicken, are often used. The chicken is an excellent model organism due to its low cost and minimal maintenance, however they present observational challenges because they are enclosed in an opaque eggshell. In order to properly view the embryo as it develops, the shell must be windowed or removed. Both windowing and ex ovo techniques have been developed to assist researchers in the study of embryonic development. However, each of the methods has limitations and challenges. Here, we present a simple, optimized ex ovo culture technique for chicken embryos that enables the observation of embryonic development from stage HH 19 into late stages of development (HH 40), when many organs have developed. This technique is easy to adopt in both undergraduate classes and more advanced research laboratories where embryo manipulations are conducted.

Optimized Ex-ovo Culturing of Chick Embryos to Advanced Stages of Development

Viewing and accessing the chicken embryo during development can be challenging. We have developed an ex ovo method that is simple, cost effective, and can easily be used in a classroom or research setting. This method provides access to the embryo into late stages of embryonic development (HH 40).

Research in anatomy, embryology, and developmental biology has largely relied on the use of model organisms. In order to study development in live embryos ...

An Optogenetic Approach for Assessing Formation of Neuronal Connections in a Co-culture System

Here we describe a protocol to generate a co-culture consisting of 2 different neuronal populations. Induced pluripotent stem cells (iPSCs) are reprogrammed from human fibroblasts using episomal vectors. Colonies of iPSCs can be observed 30 days after initiation of fibroblast reprogramming. Pluripotent colonies are manually picked and grown in neural induction medium to permit differentiation into neural progenitor cells (NPCs). iPSCs rapidly convert into neuroepithelial cells within 1 week and retain the capability to self-renew when maintained at a high culture density. Primary mouse NPCs are differentiated into astrocytes by exposure to a serum-containing medium for 7 days and form a monolayer upon which embryonic day 18 (E18) rat cortical neurons (transfected with channelrhodopsin-2 (ChR2)) are added. Human NPCs tagged with the fluorescent protein, tandem dimer Tomato (tdTomato), are then seeded onto the astrocyte/cortical neuron culture the following day and allowed to differentiate for 28 to 35 days. We demonstrate that this system forms synaptic connections between iPSC-derived neurons and cortical neurons, evident from an increase in the frequency of synaptic currents upon photostimulation of the cortical neurons. This co-culture system provides a novel platform for evaluating the ability of iPSC-derived neurons to create synaptic connections with other neuronal populations.

A protocol to generate a co-culture system consisting of neurons derived from induced pluripotent stem cells (iPSCs), primary cortical neurons and astrocytes is described. This co-culture system allows detection of the formation of synaptic contacts and circuits between new, iPSC-derived neurons and pre-existing cortical neurons expressing channelrhodopsin-2.

Here we describe a protocol to generate a co-culture consisting of 2 different neuronal populations. Induced pluripotent stem cells (iPSCs) are ...

Generating CRISPR/Cas9 Mediated Monoallelic Deletions to Study Enhancer Function in Mouse Embryonic Stem Cells

Enhancers control cell identity by regulating tissue-specific gene expression in a position and orientation independent manner. These enhancers are often located distally from the regulated gene in intergenic regions or even within the body of another gene. The position independent nature of enhancer activity makes it difficult to match enhancers with the genes they regulate. Deletion of an enhancer region provides direct evidence for enhancer activity and is the gold standard to reveal an enhancer's role in endogenous gene transcription. Conventional homologous recombination based deletion methods have been surpassed by recent advances in genome editing technology which enable rapid and precisely located changes to the genomes of numerous model organisms. CRISPR/Cas9 mediated genome editing can be used to manipulate the genome in many cell types and organisms rapidly and cost effectively, due to the ease with which Cas9 can be targeted to the genome by a guide RNA from a bespoke expression plasmid. Homozygous deletion of essential gene regulatory elements might lead to lethality or alter cellular phenotype whereas monoallelic deletion of transcriptional enhancers allows for the study of cis-regulation of gene expression without this confounding issue. Presented here is a protocol for CRISPR/Cas9 mediated deletion in F1 mouse embryonic stem (ES) cells (Mus musculus129 x Mus castaneus). Monoallelic deletion, screening and expression analysis is facilitated by single nucleotide polymorphisms (SNP) between the two alleles which occur on average every 125 bp in these cells.

Experimental validation of enhancer activity is best approached by loss-of-function analysis. Presented here is an efficient protocol that uses CRISPR/Cas9 mediated deletion to study allele-specific regulation of gene transcription in F1 ES cells which contain a hybrid genome (Mus musculus129 x Mus castaneus).

Enhancers control cell identity by regulating tissue-specific gene expression in a position and orientation independent manner. These enhancers are often ...

Technique to Target Microinjection to the Developing Xenopus Kidney

The embryonic kidney of Xenopus&#160;laevis (frog), the pronephros, consists of a single nephron, and can be used as a model for kidney disease. Xenopus embryos are large, develop externally, and can be easily manipulated by microinjection or surgical procedures. In addition, fate maps have been established for early Xenopus embryos. Targeted microinjection into the individual blastomere that will eventually give rise to an organ or tissue of interest can be used to selectively overexpress or knock down gene expression within this restricted region, decreasing secondary effects in the rest of the developing embryo. In this protocol, we describe how to utilize established Xenopus fate maps to target the developing Xenopus kidney (the pronephros), through microinjection into specific blastomere of 4- and 8-cell embryos. Injection of lineage tracers allows verification of the specific targeting of the injection. After embryos have developed to stage 38 - 40, whole-mount immunostaining is used to visualize pronephric development, and the contribution by targeted cells to the pronephros can be assessed. The same technique can be adapted to target other tissue types in addition to the pronephros.

Technique to Target Microinjection to the Developing Xenopus Kidney

Here, we present a protocol to use fate maps and lineage tracers to target injections into individual blastomeres that give rise to the kidney of Xenopus laevis embryos.

The embryonic kidney of Xenopus&#160;laevis (frog), the pronephros, consists of a single nephron, and can be used as a model for kidney disease. Xenopus ...

Gene Transfer into the Chicken Auditory Organ by In Ovo Micro-electroporation

Chicken embryos are ideal model systems for studying embryonic development as manipulations of gene function can be conducted with relative ease in ovo. The inner ear auditory sensory organ is critical for our ability to hear. It houses a highly specialized sensory epithelium that consists of mechano-transducing hair cells (HCs) and surrounding glial-like supporting cells (SCs). Despite structural differences in the auditory organs, molecular mechanisms regulating the development of the auditory organ are evolutionarily conserved between mammals and aves. In ovo electroporation is largely limited to early stages at E1 - E3. Due to the relative late development of the auditory organ at E5, manipulations of the auditory organ by in ovo electroporation past E3 are difficult due to the advanced development of the chicken embryo at later stages. The method presented here is a transient gene transfer method for targeting genes of interest at stage E4 - E4.5 in the developing chicken auditory sensory organ via in ovo micro-electroporation. This method is applicable for gain- and loss-of-functions with conventional plasmid DNA-based expression vectors and can be combined with in ovo cell proliferation assay by adding EdU (5-ethynyl-2&#180;-deoxyuridine) to the whole embryo at the time of electroporation. The use of green or red fluorescent protein (GFP or RFP) expression plasmids allows the experimenter to quickly determine whether the electroporation successfully targeted the auditory portion of the developing inner ear. In this method paper, representative examples of GFP electroporated specimens are illustrated; embryos were harvested 18 - 96 hr&#160;after electroporation and targeting of GFP to the pro-sensory area of the auditory organ was confirmed by RNA in situ hybridization. The method paper also provides an optimized protocol for the use of the thymidine analog EdU to analyze cell proliferation; an example of an EdU based cell proliferation assay that combines immuno-labeling and click EdU chemistry is provided.

Gene Transfer into the Chicken Auditory Organ by In Ovo Micro-electroporation

The auditory organ mediates hearing. Here we present a modified in ovo micro-electroporation method optimized for studying auditory progenitor cell proliferation and differentiation in the developing chicken auditory organ.

Chicken embryos are ideal model systems for studying embryonic development as manipulations of gene function can be conducted with relative ease in ovo. ...

A Submerged Filter Paper Sandwich for Long-term Ex Ovo Time-lapse Imaging of Early Chick Embryos

Due to its availability, low cost, flat geometry, and transparency, the ex ovo chick embryo has become a major vertebrate animal model for the study of morphogenetic events, such as gastrulation2, neurulation3-5, somitogenesis6, heart bending7,8, and brain formation9-13, during early embryogenesis. Key to understanding morphogenetic processes is to follow them dynamically by time-lapse imaging. The acquisition of time-lapse movies of chick embryogenesis ex ovo has been limited either to short time windows or to the need for an incubator to control temperature and humidity around the embryo14. Here, we present a new technique to culture chick embryos ex ovo for high-resolution time-lapse imaging using transmitted light microscopy. The submerged filter paper sandwich is a variant of the well-established filter paper carrier technique (EC-culture)1 and allows for the culturing of chick embryos without the need for a climate chamber. The embryo is sandwiched between two identical filter paper carriers and is kept fully submerged in a simple, temperature-controlled medium covered by a layer of light mineral oil. Starting from the primitive streak stage (Hamburger-Hamilton stage 5, HH5)15 up to at least the 28-somite stage (HH16)15, embryos can be cultured with either their ventral or dorsal side up. This allows the acquisition of time-lapse movies covering about 30 hr of embryonic development. Representative time-lapse frames and movies are shown. Embryos are compared morphologically to an embryo cultured in the standard EC-culture.
The submerged filter paper sandwich provides a stable environment to study early dorsal and ventral morphogenetic processes. It also allows for live fluorescence imaging and micromanipulations, such as microsurgery, bead implantation, microinjection, gene silencing, and electroporation, and has a strong potential to be combined with immersion objectives for laser-based imaging (including light-sheet microscopy).

A Submerged Filter Paper Sandwich for Long-term Ex Ovo Time-lapse Imaging of Early Chick Embryos

Here, we present a new technique to culture chick embryos ex ovo for time-lapse imaging using transmitted light and fluorescence microscopy. The submerged filter paper sandwich is a variant of the well-established filter paper carrier technique1 that allows for the culturing of chick embryos fully-submerged in a liquid culture medium.

Due to its availability, low cost, flat geometry, and transparency, the ex ovo chick embryo has become a major vertebrate animal model for the study of ...

In Ovo Electroporation in the Chicken Auditory Brainstem

Electroporation is a method that introduces genes of interest into biologically relevant organisms like the chicken embryo. It is long established that the chicken embryo is an effective research model for studying basic biological functions of auditory system development. More recently, the chicken embryo has become particularly valuable in studying gene expression, regulation and function associated with hearing. In ovo electroporation can be used to target auditory brainstem regions responsible for highly specialized auditory functions. These regions include the chicken nucleus magnocellularis (NM) and nucleus laminaris (NL). NM and NL neurons arise from distinct precursors of rhombomeres 5 and 6 (R5/R6). Here, we present in ovo electroporation of plasmid-encoded genes to study gene-related properties in these regions. We show a method for spatial and temporal control of gene expression that promote either gain or loss of functional phenotypes. By targeting auditory neural progenitor regions associated with R5/R6, we show plasmid transfection in NM and NL. Temporal regulation of gene expression can be achieved by adopting a tet-on vector system. This is a drug inducible procedure that expresses the genes of interest in the presence of doxycycline (Dox). The in ovo electroporation technique &#8211; together with either biochemical, pharmacological, and or in vivo functional assays &#8211; provides an innovative approach to study auditory neuron development and associated pathophysiological phenomena.

In Ovo Electroporation in the Chicken Auditory Brainstem

Auditory brainstem neurons of avians and mammals are specialized for fast neural encoding, a fundamental process for normal hearing functions. These neurons arise from distinct precursors of embryonic hindbrain. We present techniques utilizing electroporation to express genes in the hindbrain of chicken embryos to study gene function during auditory development.

Electroporation is a method that introduces genes of interest into biologically relevant organisms like the chicken embryo. It is long established that ...

A Novel Mammary Fat Pad Transplantation Technique to Visualize the Vessel Generation of Vascular Endothelial Stem Cells

Endothelial cells (ECs) are the fundamental building blocks of the vascular architecture and mediate vascular growth and remodeling to ensure proper vessel development and homeostasis. However, studies on endothelial lineage hierarchy remain elusive due to the lack of tools to gain access as well as to directly evaluate their behavior in vivo. To address this shortcoming, a new tissue model to study angiogenesis using the mammary fat pad has been developed. The mammary gland develops mostly in the postnatal stages, including puberty and pregnancy, during which robust epithelium proliferation is accompanied by extensive vascular remodeling. Mammary fat pads provide space, matrix, and rich angiogenic stimuli from the growing mammary epithelium. Furthermore, mammary fat pads are located outside the peritoneal cavity, making them an easily accessible grafting site for assessing the angiogenic potential of exogenous cells. This work also describes an efficient tracing approach using fluorescent reporter mice to specifically label the targeted population of vascular endothelial stem cells (VESCs) in vivo. This lineage tracing method, coupled with subsequent tissue whole-mount microscopy, enable the direct visualization of targeted cells and their descendants, through which the proliferation capability can be quantified and the differentiation commitment can be fate-mapped. Using these methods, a population of bipotent protein C receptor (Procr) expressing VESCs has recently been identified in multiple vascular systems. Procr+ VESCs, giving rise to both new ECs and pericytes, actively contribute to angiogenesis during development, homeostasis, and injury repair. Overall, this manuscript describes a new mammary fat pad transplantation and in vivo lineage tracing techniques that can be used to evaluate the stem cell properties of VESCs.

This work demonstrates a novel approach to assess the proliferation, differentiation, and vessel-forming potential of vascular endothelial stem cells (VESCs) through mammary fat pad transplantation followed by whole-mount tissue preparation for microscopic observation. A lineage tracing strategy to investigate the behavior of VESCs in vivo is also presented.

Endothelial cells (ECs) are the fundamental building blocks of the vascular architecture and mediate vascular growth and remodeling to ensure proper ...

Organotypic Culture Method to Study the Development Of Embryonic Chicken Tissues

The embryonic chicken is commonly used as a reliable model organism for vertebrate development. Its accessibility and short incubation period makes it ideal for experimentation. Currently, the study of these developmental pathways in the chicken embryo is conducted by applying inhibitors and drugs at localized sites and at low concentrations using a variety of methods. In vitro tissue&#160;culturing is a technique that enables the study of tissues separated from the host organism, while simultaneously bypassing many of the physical limitations present when working with whole embryos, such as the susceptibility of embryos to high doses of potentially lethal chemicals. Here, we present an organotypic culturing protocol for culturing the embryonic chicken half head in vitro, which presents new opportunities for the examination of developmental processes beyond the currently established methods.

Here, we present an organotypic culturing protocol to grow embryonic chicken organs in vitro. Using this method, the development of embryonic chicken tissue can be studied, while maintaining a high degree of control over the culture environment.

The embryonic chicken is commonly used as a reliable model organism for vertebrate development. Its accessibility and short incubation period makes it ...