Can the velocity of cytoplasmic movement reveal an embryo’s chances of implantation?

21 09 2026

Can something as subtle as the velocity of an embryo’s cytoplasmic movement tell us about its chances of implanting in the uterine lining? Researchers from the Faculty of Biology at the University of Warsaw have shown that, if this velocity is measured in a late blastocyst, the answer may be: yes. This discovery has significant potential for practical applications, as it could facilitate the selection of embryos with greater developmental potential in in vitro fertilization procedures, which are used, among other purposes, to treat infertility.

The World Health Organization estimates that infertility affects approximately one in six people. In in vitro fertilization procedures, the recommended standard is to transfer a single embryo into the uterus. This prevents multiple pregnancies, but at the same time increases the importance of accurately assessing embryo quality. Clinics base their selection primarily on the embryo’s morphology and on observing the rate and pattern of its divisions. These methods provide a great deal of information, but they still do not reliably predict whether an embryo will actually implant in the uterus.

This was precisely the gap that the authors of the study set out to fill. Previous research had indicated that the velocity of cytoplasmic movement could reflect the quality of both immature and freshly fertilized mouse oocytes. However, it was not known whether a similar signal could be detected at later stages of development – in the blastocyst – and, in particular, whether it was related to the embryo’s actual ability to implant. The researchers were also interested in whether the velocity of cytoplasmic movement could reveal abnormalities associated with keratins, important components of the cell cytoskeleton, as well as those related to the aging of oocytes.

The team worked with mouse embryos at the blastocyst stage, that is, just before the period when an embryo can implant in the uterus. Based on short (15-minute) recordings of the embryos and advanced computer-based image analysis, they calculated the velocity of cytoplasmic movement in individual cells. The study focused on cytoplasmic velocity in the cells forming the outer layer of the blastocyst (trophectoderm). The researchers then examined whether there was a relationship between the velocity of cytoplasmic movement and the embryo’s ability to implant in vitro, that is, to form an outgrowth.

The researchers found that late blastocysts with slower cytoplasmic movement in the polar trophectoderm (the part of the trophectoderm surrounding the inner cells that will later develop into the fetal body) formed a proper outgrowth almost four times more often than embryos with faster movement (76.5% vs. 20%). No such relationship was observed in younger blastocysts or in the mural trophectoderm (located opposite the polar trophectoderm and surrounding the blastocyst cavity). Importantly, the researchers showed that the embryo imaging procedure did not reduce their developmental potential and was therefore safe for the embryos. At the same time, the velocity of cytoplasmic movement did not reflect changes associated with oocyte aging, while disruptions of the keratin cytoskeleton affected it only to a limited extent.

These findings do not yet mean that fertility clinics have a ready-to-use new embryo quality test. The experiment was conducted on mouse embryos, and implantation was assessed using a simplified in vitro model. The authors therefore emphasize the need to confirm this relationship in other species, including humans, and under in vivo conditions before its use in clinical practice can be considered. Nevertheless, the study demonstrates something important: beyond an embryo’s morphology and the rate of its divisions, its biomechanical properties may also provide valuable information.

The article, ’Cytoplasmic velocity in polar trophectodermal cells reflects embryonic ability to implant in vitro’ was published in Biology of Reproduction. The authors affiliated with the Faculty of Biology at the University of Warsaw are Agnieszka Walewska, PhD, Iga Pilaszek, MSc and Anna Ajduk, PhD, DSc, University Professor from the Department of Embryology, Institute of Developmental Biology and Biomedical Sciences. The study was carried out in cooperation with the Medical University of Bialystok. It was funded by the National Science Centre, Poland, under the OPUS grant UMO-2020/39/B/NZ5/02962, led by Anna Ajduk, PhD, DSc, University Professor.

Link to the article: https://academic.oup.com/biolreprod/advance-article/doi/10.1093/biolre/ioag190/8785056