Investigation Of Developmental Morphology On Mouse Embryos Of Different Stages With Gold Nanorods As Contrast Agents Using SD-OCT

High-resolution,non-invasive and real-time rapid live imaging for the embryos after implantation is a key way to study the early embryonic development process,meanwhile has great clinical guiding significance for promoting the development of embryology.The traditional pathological tissue slicing technique has the limitation of high professional requirements and inability to perform real-time in vivo imaging.Optical coherence tomography(OCT)is a new type of optical imaging technology that can realize non-invasive real-time imaging of living tissue.It has great application prospects in basic research and clinical diagnosis of embryonic development.This subject was based on Spectral-domain OCT(SD-OCT)system for non-invasive,real-time 2D/3D imaging of early mouse E9.5 and E10.5.As an optical contrast agent,gold nanorods were introduced for the first time to further study its effect on image contrast,signal amplitude and imaging depth.Quantitative analysis of mouse heart areas at different depths and hearts volume of live embryos for the first time.The 2D anatomical structure and the size of heart area of mouse embryos at different stages after incubation with gold nanorods with depth were compared.Methods:Firstly,E9.5 and E10.5 embryos were cultured ex vivo for 3 h and 6 h in culture medium with gold nanorods at concentrations of 10 ?g/mL,20 ?g/mL,and 50 ?g/mL,respectively,and gold ion content in placentas and embryos were detected by ICP.Then,2D and 3D SD-OCT imaging were performed on embryos cultured ex vivo.Finally,the volume of the hearts were calculated by selecting the heart region of different depths embryo section.Results:Firstly,we confirmed that the nanorods can be successfully obtained by the embryos through this culture method.Quantitative OCT signal amplitudes did not show a linear increase with the concentration of gold nanorods.E9.5 and E10.5 had the highest absorption when the gold nanorods concentration was 20pg/mL and 10?g/mL respectively.For the E10.5,the results showed that after adding the gold nanorods,the structural information,image contrast and organizational resolution of E10.5 3D image was significantly improved compared with the control group.The same results could be obtained from the observation of multiple profiles at the same depth.And the heart volume of mouse embryos in different stages were successfully calculated by selected the heart region.OCT technology has the advantages of non-invasiveness,high sensitivity and rapid real-time imaging.The combination of gold nanorods with high scattering properties can not only realize the research of early-stage morphological development of live embryos,but also improve the imaging performance of OCT and expand the application range.Accurate quantification of different cross-sectional areas and reconstructed volumes during cardiac development provides a important reference and new detection methods for clinical research on embryonic development.