This work was supported by Key Research and Development projects in Xinjiang Uygur Autonomous Region (2017B03014, 2017B03014-1, 2017B03014-2, 2017B03014-3).

1. Preparation before exposure
<ol>
	<li>Select fertilized quail eggs born on the same day for the exposure test.</li>
	<li>Select quail eggs with similar weights. Each fertilized quail egg is about 10-12 g.</li>
	<li>Fully clean all fertilized quail eggs from external feces and other debris.</li>
	<li>Sterilize each pre-hatched fertilized quail egg and the eggs to be used (Choose eggs with similar shell shape, especially the tip of the egg) with an antibiotic solution (penicillin and streptomycin, 1:1000, room temperature). Sterilize the incubator with 75% ethanol.</li>
	<li>Open the eggs with the blunt end of a dental drill, leaving the eggshell at the tip for further use. Before transferring the fertilized eggs, the contents of the eggs are poured out. This is to keep the moisture of the eggshell.&#160;The opening diameter of the egg was about 3 cm. 
	NOTE: To reduce the damage to the quail embryo, use a dental drill to open the blunt end of the egg and make the crack as smooth as possible.</li>
	<li>After sterilization, place the fertilized quail eggs in a 38 &#176;C incubator with 60% humidity for 24-48 h. Ensure that the blunt end of the quail egg faces up.</li>
	<li>During the incubation of fertilized quail eggs, sterilize the tools needed in the subsequent experiments in a sterilization pot. These tools include plastic wrap, a beaker, sterile water, pipette tips, surgical straight scissors, tweezers, and a spoon. 
	NOTE:&#160;Use a film with a temperature tolerance high enough to avoid problems with the high-temperature sterilization.</li>
</ol>
2. Hatching the quail egg without a shell
<ol>
	<li>Transfer the pre-hatched fertilized quail eggs from the incubator to a clean bench and lay them flat on the container to stabilize them for about 1-2 min.</li>
	<li>Use scissors (12.5 cm surgical straight scissor) to poke&#160;a small hole (diameter 3 mm) in the central axis of the pre-hatched fertilized quail eggs and to cut 1-2 cm small opening. Carefully transfer the egg white and yolk of the fertilized quail eggs to the cut eggshell. 
	NOTE: When cutting a small opening with scissors, avoid touching of the yolk of quail eggs.</li>
	<li>Add the control solution (without MPs) and the exposed solution of different masses (0.1, 0.2, and 0.3 mg) of microplastics with three particle sizes (100, 200, and 500 nm) to the egg contents by pipette. At the same time, add 1 drop&#160;of penicillin and 1 drop of streptomycin with a 1 mL syringe.</li>
	<li>Cover the opening of the eggshell with the sterilized film (step 1.6).</li>
	<li>According to step 2.1-2.4, treat all the fertilized quail eggs.</li>
	<li>Place the transferred quail embryos into the 38 &#176;C incubator with 60% humidity for the necessary period. In this experiment, use an egg rotation angle of &#177;30&#176;. Turn the eggs once an hour. 
	&#8203;NOTE: The transfer should be as fast as possible, which requires more practice at the early stage.</li>
</ol>
3. Sample collection
<ol>
	<li>After seven days of culture, remove well-developed embryos observed by the naked eye from the yolk and wash with phosphate buffered solution (PBS).</li>
	<li>Dry the surplus solution outside the cleaned embryo with absorbent paper and weigh in a clean Petri dish.</li>
	<li>Open the whole chest cavity, separate the liver and the heart from the viscera with needle-nose pliers, and place in 1.5 mL centrifuge tubes immediately after clearing.</li>
	<li>Quickly record the weight on an electronic balance and calculate the hepatosomatic index (HIS = liver weight / body weight x 100). Measure the length of the sternum and body.</li>
	<li>Based on the above indicators, evaluate the impact of MPs on embryonic development. 
	&#8203;NOTE: Embryo quality here refers to the quality of yolk removal.</li>
</ol>
4. Data analysis
<ol>
	<li>Report the experimental data in the form of mean &#177; standard error (SEM).</li>
	<li>Use single-factor analysis of variance to compare the means of multiple groups of samples. The significant difference value was &#945; = 0.05.</li>
</ol>

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The authors have nothing to disclose. All authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work of this paper.

This paper provides an effective experimental scheme to evaluate quail embryo development by detecting the basic development indexes. However, there are still some limitations to this experiment. 
First, the mortality of quail embryos in the later stage of hatching is higher because of the shell-less hatching. There are artificially uncontrollable factors such as the destruction of normal protein ratio in the experimental process. We limited the exposure time of embryos to ensure the accuracy ...

The production of plastic waste was about 6300 Mt in 2015, one-tenth of which was recycled, and the rest was burned or buried underground. It is estimated that about 12,000 Mt of plastic waste would be buried underground by 20501. With the international community&#39;s attention to plastic waste, Thompson first proposed the concept of microplastics in 20042. Microplastics (MPs) refer to small particle plastics with a particle diameter less than 5 mm. At present, researchers have detected the ubiquitous presence of MPs in the coastline of various continents, the Atlantic Islands, inland lakes, the Arctic, and deep-sea habitats3,4,5,6,7. Therefore, more researchers have begun to study the environmental hazards of MPs.
Organisms could ingest MPs in the environment. MPs were found in the digestive tract of 233 marine organisms worldwide (including 100% turtle species, 36% seal species, 59% whale species, 59% seabird species, 92 kinds of sea fish, and 6 kinds of invertebrates)8. Moreover, MPs may block the organisms&#39; digestive system, accumulate, and migrate in their bobies9. It has been found that MPs can be transferred via the food chain, and their intake differs with the changes of habitat, growth stage, feeding habits, and food sources10. Some researchers reported the existence of MPs in the droppings of seabirds11, which means that seabirds act as the carrier of MPs. In addition, ingestion of MPs can affect health of some organisms. For example, MPs can be entangled in the gastrointestinal tract, thus increasing the mortality of cetaceans12.
MPs alone have toxic effects on organisms as well as joint toxic effects on organisms with other pollutants. Ingestion of environmental-related concentrations of plastic debris may disturb the endocrine system function of adult fish13. The size of microplastics is one of the important factors that affect their uptake and accumulation by organisms14,15. The small-size plastics, especially the nanosize plastics, are prone to interaction with cells and organisms with high toxicity16,17,18,19. Although the harmful effects of nano-particle size microplastics on organisms exceed the current research level, the detection and quantification of microplastics with sizes less than several micrometers, especially the submicron/nano-plastics in the environment, is still a great challenge. In addition, nano-plastics also have some effects on embryos. Polystyrene can damage the development of sea urchin embryos by regulating protein and gene profiles20.
To explore the potential impact of MPs on organisms, we conducted this study. Due to the similarity between bird embryos and human embryos, they are usually used in developmental biology research21 including angiogenesis and antiangiogenesis, tissue engineering, biomaterial implant, and brain tumors22,23,24. Bird embryos have the advantages of low cost, a short culture cycle and easy operation25,26. Therefore, we chose quail embryos with a short growth cycle as the experimental animal in this study. Simultaneously, we can directly observe the morphological changes of quail embryos exposed to MPs during the embryonic development stage using an eggshell-free hatching technology. The experimental materials used were polypropylene (PP) and polystyrene (PS). Because PP and PS27 account for the largest proportion of polymer types obtained in sediments and water bodies worldwide, the most common polymer types extracted from captured marine organisms are ethylene and propylene28. This experimental protocol describes the whole process for visual evaluation of toxicological effects of MPs on quail embryos exposed to MPs. We can easily extend this method to examine other pollutants&#39; toxicity to embryo development of other oviparous animals.

<table><tbody><tr><td>&amp;nbsp;Multi sample tissue grinder</td><td>Shanghai Jingxin Industrial Development Co., Ltd.</td><td>Tissuelyser-24</td><td>Grind large-sized plastics into small-sized ones at low temperature</td></tr><tr><td>Electronic balance</td><td>OHAUS corporation</td><td>PR Series Precision</td><td>Used for weighing</td></tr><tr><td>Fertilized quail eggs</td><td>Guangzhou Cangmu Agricultural Development Co., Ltd.</td><td></td><td>Quail eggs for hatching without shell</td></tr><tr><td>Fluorescent polypropylene particles</td><td>Foshan Juliang Optical Material Co., Ltd.</td><td></td><td>Types of plastics selected for the experiment</td></tr><tr><td>Incubator</td><td>Shandong, Bangda Incubation Equipment Co., Ltd.</td><td>264 pc</td><td>Provide a place for embryo growth and development</td></tr><tr><td>Nanometer-scale polystyrene microspheres</td><td>Xi&amp;rsquo;an Ruixi Biological Technology Co., Ltd.</td><td>100 nm, 200 nm, 500 nm</td><td>Types of plastics selected for the experiment</td></tr><tr><td>Steel ruler</td><td>Deli Group</td><td>20 cm</td><td>Used to measure&amp;nbsp; length</td></tr><tr><td>Vertical heating pressure steam sterilizer</td><td>Shanghai Shenan Medical Instrument Factory</td><td>LDZM-80KCS-II</td><td>Sterilize the experimental articles</td></tr></tbody></table>

ecotoxicological effects of microplastics on bird embryo development by hatching without eggshell

Microplastics are an emerging global pollutant type that poses a great health threat to animals due to their uptake and translocation in animal tissues and organs. Ecotoxicological effects of microplastics on the development of bird embryos are not known. The bird egg is a complete development and nutrition system, and the entire embryo development occurs in the eggshell. Therefore, a direct record of bird embryo development under the stress of pollutants such as microplastics is highly limited by the opaque eggshell in traditional hatching. In this study, the effects of microplastics on quail embryo development were visually monitored by hatching without an eggshell. The main steps include the cleaning and disinfection of fertilized eggs, the incubation before exposure, the short-term incubation after exposure, and the sample extraction. The results show that compared with the control group, the wet weight and body length of the microplastics-exposed group displayed a statistical difference and the liver proportion of the whole exposed group significantly increased. Additionally, we evaluated external factors that affect the incubation: temperature, humidity, egg rotation angle, and other conditions. This experimental method provides valuable information on the ecotoxicology of microplastics and a novel way to study the adverse effects of pollutants on the development of embryos.

For the analysis of experimental data, we compared wet weight, body length, sternum length and the change of hepatosomatic index between the control group and the 6 experimental groups, measuring and reflecting the quail embryos&#39; growth and development from a macro perspective. We detected six normal quail embryos in each group. Each embryo reached the required Hamburger and Hamilton (HH) stage.
In Figure 1, we transferred the pre-hatched fertilized quail egg ...

Watch this Scientific Journal Video about Ecotoxicological Effects of Microplastics on Bird Embryo Development by Hatching without Eggshell at JoVE.com

Ecotoxicological Effects of Microplastics on Bird Embryo Development by Hatching without Eggshell

This paper introduces a method of hatching without using an eggshell for toxicological studies of particle pollutants such as microplastics.

Microplastics are an emerging global pollutant type that poses a great health threat to animals due to their uptake and translocation in animal tissues ...

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4.4K Views.  Chinese Academy of Sciences. Dit experiment zal vier delen omsluiten. Voorbereiding voor blootstelling, uitkomen kwartelei zonder schaal, incubatieproces en een monsterverzameling, en representatieve resultaten. Bekijk de volgende video voor het specifieke experimentele proces. In de blootstellingstest werd dezelfde partij kwartelbevruchte eieren geselecteerd voor het experiment. De eieren met een vergelijkbare grootte werden geselecteerd om de experimentele fout te verminderen. Tegelijkertijd moeten alle kwartels de eie...

Video: Ecotoxicological Effects of Microplastics on Bird Embryo Development by Hatching without Eggshell

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 ...

Developmental Biology

Windowing Chicken Eggs for Developmental Studies

The study of development has been greatly aided by the use of the chick embryo as an experimental model.  The ease of accessibility of the embryo has allowed for experiments to map cell fates using several approaches, including chick quail chimeras and focal dye labeling.  In addition, it allows for molecular perturbations of several types, including placement of protein-coated beads and introduction of plasmid DNA using in ovo electroporation.  These experiments have yielded important data on the development of the central and peripheral nervous systems.  For many of these studies, it is necessary to open the eggshell and reclose it without perturbing the embryo's growth.  The embryo can be examined at successive developmental stages by re-opening the eggshell.  While there are several excellent methods for opening chicken eggs, in this article we demonstrate one method that has been optimized for long survival times.  In this method, the egg rests on its side and a small window is cut in the shell.  After the experimental procedure, the shell is used to cover the egg for the duration of its development.  Clear plastic tape overlying the eggshell protects the embryo and helps retain hydration during the remainder of the incubation period.  This method has been used beginning at two days of incubation and has allowed survival through mature embryonic ages.

The ease of accessibility of the embryo has allowed for experiments to map cell fates using several approaches, including chick quail chimeras and focal dye labeling. In this article we demonstrate one egg preparation method that has been optimized for long survival times.

The study of development has been greatly aided by the use of the chick embryo as an experimental model.  The ease of accessibility of the embryo has ...

Biology

Assessment of the Effects of Endocrine Disrupting Compounds on the Development of Vertebrate Neural Network Function Using Multi-electrode Arrays

Bis-phenols, such as bis-phenol A (BPA) and bis-phenol-S (BPS), are polymerizing agents widely used in the production of plastics and numerous everyday products. They are classified as endocrine disrupting compounds (EDC) with estradiol-like properties. Long-term exposure to EDCs, even at low doses, has been linked with various health defects including cancer, behavioral disorders, and infertility, with greater vulnerability during early developmental periods. To study the effects of BPA on the development of neuronal function, we used an in vitro neuronal network derived from the early chick embryonic brain as a model. We found that exposure to BPA affected the development of network activity, specifically spiking activity and synchronization. A change in network activity is the crucial link between the molecular target of a drug or compound and its effect on behavioral outcome. Multi-electrode arrays are increasingly becoming useful tools to study the effects of drugs on network activity in vitro. There are several systems available in the market and, although there are variations in the number of electrodes, the type and quality of the electrode array and the analysis software, the basic underlying principles, and the data obtained is the same across the different systems. Although currently limited to analysis of two-dimensional in vitro cultures, these MEA systems are being improved to enable in vivo network activity in brain slices. Here, we provide a detailed protocol for embryonic exposure and recording neuronal network activity and synchrony, along with representative results.

Exposure to environmental toxins can acutely impact developing embryos. Endocrine disrupting chemicals such as bisphenols are known to adversely affect the nervous system. Here we describe a protocol using an in vitro vertebrate (chick embryo) neuronal network model to study the functional impact of toxin exposure on early embryos.

Bis-phenols, such as bis-phenol A (BPA) and bis-phenol-S (BPS), are polymerizing agents widely used in the production of plastics and numerous everyday ...

Long-term Behavioral and Reproductive Consequences of Embryonic Exposure to Low-dose Toxicants

Bisphenols, such as bisphenol A (BPA) and bisphenol S (BPS) are polymerizing agents widely used in the production of plastics and numerous everyday-use products. Based on their chemical structure and estradiol-like biological properties, they have been classified as endocrine disrupting compounds (EDC). Long-term exposure to EDCs, even at low doses, has been linked to various health defects including cancer, behavioral disorders and infertility, with greater vulnerability indicated during early developmental periods. Cellular and molecular studies with the genetically tractable nematode model Caenorhabditis elegans have demonstrated that exposure to BPA causes apoptosis, embryonic lethality and disruption in the DNA repair mechanisms. We have previously reported that exposure of C. elegans embryos to low doses of different bisphenols decreases fecundity. In addition, we have shown that the effects of exposure during the very early stages of development persist into adulthood as assayed by quantifying habituation behavior, a form of non-associative learning. Here, we provide detailed protocols for embryonic exposure to low-dose EDCs as well as the associated fecundity and anterior touch habituation assays, along with representative results.

Exposure to environmental toxicants can acutely impact development with long-term effects. Detailed protocols are provided to illustrate a strategy using an effective lab model to study the effect of early embryonic exposure to bisphenol A. We provide fecundity and behavioral assays to monitor the effectiveness of our toxicant exposure bio-assays.

Bisphenols, such as bisphenol A (BPA) and bisphenol S (BPS) are polymerizing agents widely used in the production of plastics and numerous everyday-use ...

Discovery of Metastatic Regulators using a Rapid and Quantitative Intravital Chick Chorioallantoic Membrane Model

Recent advances in cancer research has illustrated the highly complex nature of cancer metastasis. Multiple genes or genes networks have been found to be involved in differentially regulating cancer metastatic cascade genes and gene products dependent on the cancer type, tissue, and individual patient characteristics. These represent potentially important targets for genetic therapeutics and personalized medicine approaches. The development of rapid screening platforms is essential for the identification of these genetic targets.
The chick chorioallantoic membrane (CAM) is a highly vascularized, collagen rich membrane located under the eggshell that allows for gas exchange in the developing embryo. Due to the location and vascularization of the CAM, we developed it as an intravital human cancer metastasis model that allows for robust human cancer cell xenografting and real-time imaging of cancer cell interactions with the collagen rich matrix and vasculature. 
Using this model, a quantitative screening platform was designed for the identification of novel drivers or suppressors of cancer metastasis. We transduced a pool of head and neck HEp3 cancer cells with a complete human genome shRNA gene library, then injected the cells, at low density, into the CAM vasculature. The cells proliferated and formed single-tumor cell colonies. Individual colonies that were unable to invade into the CAM tissue were visible as a compact colony phenotype and excised for identification of the transduced shRNA present in the cells. Images of individual colonies were evaluated for their invasiveness. Multiple rounds of selections were performed to decreases the rate of false positives. Individual, isolated cancer cell clones or newly engineered clones that express genes of interest were subjected to primary tumor formation assay or cancer cell vasculature co-option analysis. In summary we present a rapid screening platform that allows for anti-metastatic target identification and intravital analysis of a dynamic and complex cascade of events.

This is an effective method to screen for suppressors or drivers of cancer metastasis. Cells, transduced with an expression library, are injected into the chicken chorioallantoic membrane vasculature to form metastatic colonies. Colonies having decreased or increased invasiveness are excised, expanded, reinjected to confirm their phenotype, and finally, analyzed using high throughput sequencing.

Recent advances in cancer research has illustrated the highly complex nature of cancer metastasis. Multiple genes or genes networks have been found to be ...

Cancer Research

Accumulation and Distribution of Fluorescent Microplastics in the Early Life Stages of Zebrafish

As a new type of environmental pollutant, microplastic has been widely found in the aquatic environment and poses a high threat to aquatic organisms. The bioaccumulation of microplastics plays a key role in their toxic effects; however, as a particulate, their bioaccumulations are different from many other pollutants. Described here is a feasible method to visually determine the accumulation and distribution of microplastics in zebrafish embryos or larvae using fluorescent microplastics. Embryos are exposed to different concentrations (0.1, 1, and 10 mg/L) of fluorescent microplastics with a diameter of 500 nm for 120 h. It is shown in the results that microplastics can bioaccumulate in zebrafish embryos/larvae in a concentration-dependent manner. Before hatching, strong fluorescence is found around the embryonic chorion; while in zebrafish larvae, the yolk sac, pericardium, and gastrointestinal tract are the main accumulated sites of microplastics. The results demonstrate the uptake and internalization of microplastics in zebrafish at early life stages, which will provide basis for better understanding the impact of microplastics on aquatic animals.

Zebrafish embryos/larvae develop externally and are optically transparent. The bioaccumulation of microplastics in fish at early life stages is readily assessed with fluorescently labeled microbeads.

As a new type of environmental pollutant, microplastic has been widely found in the aquatic environment and poses a high threat to aquatic organisms. The ...

Using Chicken Embryo as a Powerful Tool in Assessment of Developmental Cardiotoxicities

Chicken embryos are a classical model in developmental studies. During the development of chicken embryos, the time window of heart development is well-defined, and it is relatively easy to achieve precise and timely exposure via multiple methods. Moreover, the process of heart development in chicken embryos is similar to mammals, also resulting in a four-chambered heart, making it a valuable alternative model in the assessment of developmental cardiotoxicities. In our lab, the chicken embryo model is routinely used in the assessment of developmental cardiotoxicities following exposure to various environmental pollutants, including per- and polyfluoroalkyl substances (PFAS), particulate matter (PMs), diesel exhaust (DE) and nano materials. The exposure time can be freely selected based on the need, from the beginning of development (embryonic day 0, ED0) all the way to the day prior to hatch. The major exposure methods include air-cell injection, direct microinjection, and air-cell inhalation (originally developed in our lab), and the currently available endpoints include cardiac function (electrocardiography), morphology (histological assessments) and molecular biological assessments (immunohistochemistry, qRT-PCR, western blotting, etc.). Of course, the chicken embryo model has its own limitations, such as limited availability of antibodies. Nevertheless, with more laboratories starting to utilize this model, it can be used to make significant contributions to the study of developmental cardiotoxicities.

Chicken embryos, as a classical developmental model, are used in our lab to assess developmental cardiotoxicities following exposure to various environmental contaminants. Exposure methods and morphological/functional assessment methods established are described in this manuscript.

Chicken embryos are a classical model in developmental studies. During the development of chicken embryos, the time window of heart development is ...

An ex-ovo Chicken Embryo Culture System Suitable for Imaging and Microsurgery Applications

Understanding the relationships between genetic and microenvironmental factors that drive normal and malformed embryonic development is fundamental for discovering new therapeutic strategies. Advancements in imaging technology have enabled quantitative investigation of the organization and maturing of the body plan, but later stage embryonic morphogenesis is less clear. Chicken embryos are an attractive vertebrate animal model system for this application because of its ease of culture and surgical manipulation. Early embryos can be cultured for a short time on filter paper rings, which enables complete optical access for cell patterning and fate studies1,2. Studying advanced developmental processes such as cardiac morphogenesis are traditionally performed through a window of the eggshell3-5, but this technique limits optical access due to window size. We previously developed a simple method to culture whole embryos ex-ovo on hexagonal weigh boats for up to 10 days, which enabled high resolution imaging via ultrasonography6,7. These cultures were difficult to transport, limiting the types of imaging tools available for live experiments. We here present an improved shell-less culture system with a cost-effective, portable environmental chamber. Eggs were cracked onto a hammock created by a polyurethane membrane (cling wrap) affixed circumferentially to a plastic cup partially filled with sterile water. The dimensions of the circumference and depth of the hammock were both critical to maintain surface tension, while the mechanics of the hammock and water beneath helped dampen vibrations induced by transportation. A small footprint circulating water bath was also developed to enable continuous temperature control during experimentation. We demonstrate the ability to culture embryos in this way for at least 14 days without morphogenic defect or delay and employ this system in several microsurgical and imaging applications.

An ex-ovo Chicken Embryo Culture System Suitable for Imaging and Microsurgery Applications

In this article, we present a simple methodology to enable long-term ex-ovo avian embryo culture. This technique is ideal for longitudinal experimentation requiring complete optical accessibility and/or sterile transportation in avian embryos.

Understanding the relationships between genetic and microenvironmental factors that drive normal and malformed embryonic development is fundamental for ...

Analysis of Cell Differentiation, Morphogenesis, and Patterning During Chicken Embryogenesis Using the Soaked-Bead Assay

A multitude of genetic programs is activated during embryonic development that orchestrates cell differentiation to generate an astounding diversity of somatic cells, tissues, and organs. The precise activation of these genetic programs is regulated by morphogens, diffusible molecules that direct cell fate at different thresholds. Understanding how genetic activation coordinates morphogenesis requires the study of local interactions triggered by morphogens during development. The use of beads soaked in proteins or drugs implanted into distinct regions of the embryo enables studying the role of specific molecules in the establishment of digits and other developmental processes. This experimental technique provides information on the control of cell induction, cell fate, and pattern formation. Thus, this soaked bead assay is an extremely powerful and valuable experimental tool applicable to other embryonic models.

The soaked bead assay involves targeted delivery of test reagent at any developmental time point to study the regulation of cell differentiation and morphogenesis. A detailed protocol, applicable to any experimental animal model, for preparing three different types of soaked beads and implanting these in the interdigit of a chicken embryo is presented.

A multitude of genetic programs is activated during embryonic development that orchestrates cell differentiation to generate an astounding diversity of ...

The Preparation of Chicken Ex Ovo Embryos and Chorioallantoic Membrane Vessels as In Vivo Model for Contrast-Enhanced Ultrasound Imaging and Microbubble-Mediated Drug Delivery Studies

The chicken embryo and the blood-vessel rich chorioallantoic membrane (CAM) is a valuable in vivo model to investigate biomedical processes, new ultrasound pulsing schemes, or novel transducers for contrast-enhanced ultrasound imaging and microbubble-mediated drug delivery. The reasons for this are the accessibility of the embryo and vessel network of the CAM as well as the low costs of the model. An important step to get access to the embryo and CAM vessels is to take the egg content out of the eggshell. In this protocol, three methods for taking the content out of the eggshell between day 5 and&#160;8 of incubation are described thus allowing the embryos to develop inside the eggshell up to these days. The described methods only require simple tools and equipment and yield a higher survival success rate of 90% for 5-day, 75% for 6-day, 50% for 7-day, and 60% for 8-day old incubated eggs in comparison to ex ovo cultured embryos (~50%). The protocol also describes how to inject cavitation nuclei, such as microbubbles, into the CAM vascular system, how to separate the membrane containing the embryo and CAM from the rest of the egg content for optically transparent studies, and how to use the chicken embryo and CAM in a variety of short-term ultrasound experiments. The in vivo&#160;chicken embryo and CAM model is extremely relevant to investigate novel imaging protocols, ultrasound contrast agents, and ultrasound pulsing schemes for contrast-enhanced ultrasound imaging, and to unravel the mechanisms of ultrasound-mediated drug delivery.

This protocol describes three methods on how to obtain and use 5 to 8-day old chicken embryos and their chorioallantoic membrane (CAM) as an in vivo&#160;model to study contrast-enhanced ultrasound imaging and microbubble-mediated drug delivery.

Ecotoxicological Effects of Microplastics on Bird Embryo Development by Hatching without Eggshell

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