Three-dimensional X-ray microtomography of the heart of a chick embryo in the early period of embryogenesis

Relevance. The chicken embryo model is ideal for studying the development of the heart, which is the first functioning organ in embryogenesis. Particular attention is drawn to the embryonic period, when the embryonic heart is both functioning and forming, and small deviations in this process can lead to developmental anomalies. The current lack of results of accurate measurements of the morphology of the heart of a chicken embryo requires high-quality visualization, the complexity of which is determined by dynamic changes in the morphology of the heart, small size and complex spatial details of the organ. Threedimensional imaging methods are indispensable tools in this aspect, among which X-ray microtomography has special advantages.

Methods. Embryo scanning (4–8 days, embryonic stages HH22–HH34) was performed using a highresolution X-ray microtomograph Skyscan 1176. A 1% solution of phosphoric-tungstic acid was used as a contrast. Post-processing, reconstruction, visualization of 3D-images, morphometry and X-ray density assessment were carried out using software packages DataViewer (1.5.6.2), CTvox (3.3.0r1403), CT-analyser (1.18.4.0).

Results. The results obtained consist of three components: 1) general three-dimensional X-ray microtomographic visualization of chicken embryos in the early stages of embryogenesis with the designation of internal organs, allowing to determine the correct location of the heart; 2) microtomography of the heart with the designation of the main structures; 3) morphometric parameters of the embryo, heart and their X-ray density in units of the Hounsfield scale (HU). The methodological approach used has shown high efficiency. With an increase in the linear size of the chicken embryo and internal organs, including the heart, a high level of both general X-ray contrast and diffraction remains. At all the studied stages of the embryonic period of embryogenesis (4–8 days; HH22–HH34), the main visual and quantitative characteristics of cardiac morphogenesis were revealed.