An approach for analyzing migration and eventual fate of avian neural crest cells in quail-chick chimeric embryos is described. This method is a simple and straightforward technique for tracing neural crest cells during migration and differentiation that are otherwise difficult to distinguish within an unmanipulated chick embryo.
Avian embryos provide a unique platform for studying many vertebrate developmental processes, due to the easy access of the embryos within the egg. Chimeric avian embryos, in which quail donor tissue is transplanted into a chick embryo in ovo, combine the power of indelible genetic labeling of cell populations with the ease of manipulation presented by the avian embryo.
Quail-chick chimeras are a classical tool for tracing migratory neural crest cells (NCCs)1-3. NCCs are a transient migratory population of cells in the embryo, which originate in the dorsal region of the developing neural tube4. They undergo an epithelial to mesenchymal transition and subsequently migrate to other regions of the embryo, where they differentiate into various cell types including cartilage5-13, melanocytes11,14-20, neurons and glia21-32. NCCs are multipotent, and their ultimate fate is influenced by 1) the region of the neural tube in which they originate along the rostro-caudal axis of the embryo11,33-37, 2) signals from neighboring cells as they migrate38-44, and 3) the microenvironment of their ultimate destination within the embryo45,46. Tracing these cells from their point of origin at the neural tube, to their final position and fate within the embryo, provides important insight into the developmental processes that regulate patterning and organogenesis.
Transplantation of complementary regions of donor neural tube (homotopic grafting) or different regions of donor neural tube (heterotopic grafting) can reveal differences in pre-specification of NCCs along the rostro-caudal axis2,47. This technique can be further adapted to transplant a unilateral compartment of the neural tube, such that one side is derived from donor tissue, and the contralateral side remains unperturbed in the host embryo, yielding an internal control within the same sample2,47. It can also be adapted for transplantation of brain segments in later embryos, after HH10, when the anterior neural tube has closed47.
Here we report techniques for generating quail-chick chimeras via neural tube transplantation, which allow for tracing of migratory NCCs derived from a discrete segment of the neural tube. Species-specific labeling of the donor-derived cells with the quail-specific QCPN antibody48-56 allows the researcher to distinguish donor and host cells at the experimental end point. This technique is straightforward, inexpensive, and has many applications, including fate-mapping, cell lineage tracing, and identifying pre-patterning events along the rostro-caudal axis45. Because of the ease of access to the avian embryo, the quail-chick graft technique may be combined with other manipulations, including but not limited to lens ablation40, injection of inhibitory molecules57,58, or genetic manipulation via electroporation of expression plasmids59-61, to identify the response of particular migratory streams of NCCs to perturbations in the embryo’s developmental program. Furthermore, this grafting technique may also be used to generate other interspecific chimeric embryos such as quail-duck chimeras to study NCC contribution to craniofacial morphogenesis, or mouse-chick chimeras to combine the power of mouse genetics with the ease of manipulation of the avian embryo.62
The grafting of quail neural tube into host chick embryos described here is a straightforward and inexpensive technique for tracing specific subpopulations of migrating NCCs emanating from different regions along the rostro-caudal axis21,67-69. This technique takes advantage of the ease of access to avian embryos (as compared to mammalian embryos) and may be combined with other techniques, such as tissue ablation, injection of inhibitory molecules, or genetic manipulation via electroporation of expression plas…
The authors have nothing to disclose.
The authors thank members of the Lwigale laboratory for critique of the manuscript. SLG is supported by a Ruth L. Kirschstein NRSA Fellowship from the National Eye Institute (F32 EY02167301). PYL is supported by the National Eye Institute (EY018050).
Reagent | Company | Catalog number |
Chick eggs | Various – we use Texas A&M University’s Poultry Science Department, TX. | |
Quail eggs | Various – we use Ozarks Egg Company, MO. | |
Egg incubator (Digital Readout 1502 Sportsman Incubator w/Humidity 110-120 Volt AC) | www.poultrysupply.com | 1502 |
Dumont AA forceps, Inox Epoxy-coated | Fine Science Tools | 11210-10 |
Scotch tape | Any office supply store | |
Curved Iris forceps | Fine Science Tools | 11065-07 |
India ink | Any art supply store | |
Pen/Strep (Penicillin, Streptomycin) Solution | VWR International | 101447-068 |
Clear Packing tape | Any office supply store | |
Needle pulling apparatus | Narashige, Japan | PE-21 |
Pulled glass needle, made from 1.5-1.8 x 100mm borosilicate glass capillary tube | Kimble chase | 34500 99 |
Pulled glass pipette, made from 5¾” Pasteur pipette | Fisher Scientific | 13-678-6A |
Mouth pipette apparatus (aspirator tube assembly for calibrated microcapillary pipette) | Sigma-Aldrich | A5177-52A |
Dumont #5 forceps | Fine Science Tools | 11251-30 |
Tungsten wire, 0.1mm diameter | VWR International | AA10404-H2 |
Needle holders (Nickel-plated pin holder) | Fine Science Tools | 26018-17 |
QCPN antiserum | Developmental Studies Hybridoma Bank, University of Iowa | QCPN |
Alexa Fluor secondary antibody (e.g., Alexa Fluor 594 goat anti-mouse IgG1) | Invitrogen | A21125 |
Ringer’s Solution (2L):
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All reagents from Fisher Scientific |
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