Investigation Of Full-Field OCT And Morphological Study Of Early Mouse Embryo Development

Optical coherence tomography (OCT) is an emerging3D imaging modalitybased on low coherence interferometry. The technique is suitable fornon-invasive, low optical damage and high resolution tomographic visualizationof the internal structure in biological samples. For these reasons, the techniqueof OCT has become a valuable methodology in biological and medical studies.On the other hand, the mechanism of early mammalian embryonic developmentis of great importance in developmental biology. Among the related studies, dueto the limitation of the experimental conditions and the methods, earlypatterning and polarity that takes the morphological evolution as its core, stillremains a controversial issue.Therefore, in this dissertation, a novel method based on full-field OCT(FF-OCT), which was an extension of OCT, was presented in order to providethe breakthrough and new insights into the controversial issue. Using thismethod, we demonstrated a series of the interesting results.First, the system of FF-OCT was successfully established and wasimproved a lot for its application to the morphological studies of early mouseembryos. We broke through the limitation that FF-OCT was only capable ofimaging the fixed (or dead) embryos and obtained label-free3D livemorphological images of the mouse embryos at various typical developmentalstages ranged from1-cell stage to blastocyst stage for the first time. Thesestages were all of notable morphological characteristics and a great many spatialfactors that related to these early developmental stages were quantitativelyanalysed.For further analysis, we extended our work and made some successfulattempts to study the dynamics of developmental processes during early mouseembryonic lives. We focused our imaging on the controversial event of the firstcleavage to investigate3D spatial morphogenetic relationship between the twopronuclei in zygote, the2PB and the first cleavage plane. Coupled withquantitative and statistical study, we demonstrated that only27%of the first realcleavage planes passed through the2PB and only24%of the predicted first cleavage planes that defined by the two pronuclei were in good accordance withthe real cleavage planes. These results suggested that the2PB and the twopronuclei were not convincing spatial cues for the event of the first cleavage.In addition, FF-OCT was also applied to the spindle related investigations,and the first label-free3D live morphological images of the spindles within theoocytes and the zygotes were obtained with FF-OCT. The spindle relatedmorphological parameters were quantitatively measured as well.Our studies demonstrate the feasibility of FF-OCT in providing newinsights and potential breakthroughs to the controversial issues of earlymammalian embryonic development. Also, we believe that FF-OCT will offer apowerful methodology for the early embryo and the spindle related studies inmammalian developmental biology.