Vitrification is an increasingly popular method of embryo cryopreservation that is used in assisted reproductive technology. Although vitrification has high post-thaw survival rates compared to other freezing techniques, its long-term effects on embryo development are still poorly understood. We demonstrate an application of full-field optical coherence tomography (FF-OCT) to visualize the effects of vitrification on live single-cell (2 pronuclear) mouse embryos without harmful labels. Using FF-OCT, we observed that vitrification causes a significant increase in the aggregation of structures within the embryo cytoplasm, consistent with reports in literature based on fluorescence techniques. We quantify the degree of aggregation with an objective metric, the cytoplasmic aggregation (CA) score, and observe a high degree of correlation between the CA scores of FF-OCT images of embryos and of fluorescence images of their mitochondria. Our results indicate that FF-OCT shows promise as a label-free assessment of the effects of vitrification on embryo mitochondria distribution. The CA score provides a quantitative metric to describe the degree to which embryos have been affected by vitrification and could aid clinicians in selecting embryos for transfer.
Reliable Thermal Protection System (TPS) sensors are needed to achieve better designs for spacecraft (probe) heatshields
for missions requiring atmospheric aero-capture or entry/reentry. In particular, they will allow both reduced risk
and heat-shield mass minimization, which will facilitate more missions and allow increased payloads and returns. For
thermal measurements, Intelligent Fiber Optic Systems Corporation (IFOS) is providing a temperature monitoring
system involving innovative lightweight, EMI-immune, high-temperature resistant Fiber Bragg Grating (FBG) sensors
with a thermal mass near that of TPS materials together with fast FBG sensor interrogation. The IFOS fiber optic sensing
technology is highly sensitive and accurate. It is also low-cost and lends itself to high-volume production. Multiple
sensing FBGs can be fabricated as arrays on a single fiber for simplified design and reduced cost. In this paper, we
provide experimental results to demonstrate the temperature monitoring system using multi-sensor FBG arrays
embedded in small-size Super-Light Ablator (SLA) coupon, which was thermally loaded to temperatures in the vicinity
of the SLA charring temperature. In addition, a high temperature FBG array was fabricated and tested for 1000°C
Embryo cryopreservation is an increasingly common technique that allows patients to undergo multiple cycles of in vitro fertilization (IVF) without being subjected to repeated ovarian stimulation and oocyte retrieval. There are two types of cryopreservation commonly used in IVF clinics today: slow freezing and vitrification. Because vitrification has been shown to result in higher rates of embryo survival post-thaw compared to slow freezing, it is rapidly gaining popularity in clinics worldwide. However, several studies have shown that vitrification can still cause damage to embryos in the form of DNA fragmentation, altered mitochondrial distribution and changes in transcriptional activity, all of which are impossible to assess noninvasively. In this paper we demonstrate a new method of quantitatively and noninvasively assessing changes in embryo appearance due to vitrification. Using full-field optical coherence tomography (FF-OCT), we show that vitrification causes striking changes in the appearance of the cytoplasm that are not visible under conventional brightfield microscopy. Using an automated algorithm that extracts parameters to describe these changes, we show that these parameters can also predict viability in embryos that have undergone vitrification. An automated, noninvasive assessment of embryo viability after vitrification and thawing could have significant clinical impact: allowing clinicians to more accurately choose the most viable embryos to transfer back to patients could reduce the average number of IVF cycles that patients must undergo to achieve pregnancy.