An inside look at the earliest stage of life
Chao Zhou’s lab images embryo development from a single cell
In vitro fertilization has been the primary method of addressing infertility for almost five decades, yet its live birth rate is under 40%. Selecting an embryo with the optimal potential could improve the success rate, but existing practices to take time-lapse images of the developing embryos have been limited.
A team of researchers in the McKelvey School of Engineering at Washington University in St. Louis used dual-modality, 3D, time-lapse optical coherence microscopy (OCM) and brightfield (BF) imaging to monitor mouse embryo development and predict successful blastocyst formation. Results of this research, published in Communications Biology April 15, 2025, establish OCM as a viable way to choose high-quality embryos for transfer and improve success rates of in vitro fertilization.
The innovative research was conducted in the lab of Chao Zhou, professor of biomedical engineering and an internationally renowned expert in OCM and optical coherence tomography. Collaborators in the work include Fei Wang, a doctoral student in Zhou’s lab, and Ali Ahmady, associate professor of obstetrics & gynecology at WashU Medicine.
Zhou will present this work at the American Society for Reproductive Medicine (ASRM) annual meeting in October 2025. Last year, he received the Investigative Scientist Award by the ASRM Research Institute, which includes $100,000 over a two-year period to support continued work on this project. His team will construct a comprehensive database containing time-lapse OCM and BF images from many mouse embryos and develop a machine learning model to predict successful blastocyst formation based on morphological and dynamic features observed from these label-free images at various developmental stages.
Zhou said OCM is the ideal imaging technique for this work as it is a powerful tool to assess the 3D structure of mammalian embryos. The 3D approach could reveal subtle abnormalities not detectable with traditional 2D imaging,
“With a high numerical aperture objective lens, OCM provides micron-level resolutions that can resolve the embryos cellular or even subcellular features,” he said.
The team monitored the embryos from the one-cell stage to fully hatched blastocysts every 10 minutes over about six days, all within the confines of an incubator. In the early stages, OCM imaging showed individual cells as they were developing, eventually forming a blastocyst.
The researchers said this method is promising for use beyond research with applications in clinical practice.
“It provides more precise and accurate evaluations, making it a promising tool for developing morphokinetic markers that correlate with blastocyst formation,” Wang said. “It materializes in the future of IVF application in clinics as a reference for the evaluation and selection of the most viable embryos.”
Wang F, Hao S, Park K, Ahmady A, Zhou C. Label-free evaluation of mouse embryo quality using time-lapse bright field and optical coherence microscopy. Communications Biology, April 15, 2025. https://www.nature.com/articles/s42003-025-08044-5
Funding for this research was provided by the Washington University in St. Louis Startup Fund and the American Society for Reproductive Medicine/Jones Foundation Investigative Scientists Award.
Click on the topics below for more stories in those areas
Back to NewsFaculty in this story
