Microsensors and image processing for single oocyte qualification: toward multiparametric determination of the best time for fertilization

Abstract

During Intracytoplasmic Sperm Injection (ICSI) attempts, oocytes reaching metaphase II are microinjected. A morphological examination under a microscope is the usual method for determining oocyte maturity. The level of oocyte maturity is based on the meiotic status (Germinal Vesicle, metaphase I and metaphase II) of the oocytes with respect to their increasing maturity. In this paper, we summarize the studies conducted to analyze cytoplasm maturity using various microsystems and image processing. Optical microsystems are used to measure the transmission spectra and refractive index of the oocytes. We compared the transmission spectra measurements to the transmission electron microscopy results. Karhunen-Loeve Transform is also used to evaluate the maturity of the oocytes. To summarize, optical analysis techniques are a minimally invasive technology allowing cytoplasm maturity to be assessed. Oocytes should not only be qualified in terms of GV, MI or MII, but also regarding their temporal evolution over the course of these maturation stages. The ultimate aim of this work is to describe the maturation of the oocytes by a trajectory in a multidimensional space and to determine when would be the best time for successful fertilization.

Experimental measurement of human oocyte mechanical properties on a micro and nanoforce sensing platform based on magnetic springs

“…To be effective, this new technology should be fully compatible with physician's protocols and constraints, but should also provide analysis methods, preferably on a multimodal basis, to improve the reliability of oocyte maturity diagnosis. Both mechanical and optical approaches are thought effective to establish a reliable diagnosis despite the variability of the oocytes' evolution [28,29]. The mechanical tests will provide the stiffness determination of oocytes for different loads.…”

Optical interferometry based micropipette aspiration provides real-time sub-nanometer spatial resolution

“…Larger differences in RI will provide more contrast and clearer signal. As we showed by measuring the mechanical properties of hydrogel beads, the system allows for the retrieval of signals from samples that provide lower contrast (RI~1.332 21 ) than cells (RI = 1.34–2.2 22 , 23 ) in water. We believe this technique could be particularly useful for certain applications where high precision in membrane positioning and analysis are crucial such as studying lipid vesicles 24 (RI ~ 1.4–2 25 – 28 ) and biomembranes at the nanoscale, as we showed in the case of the ZP.…”

Investigation of refractive index dynamics during embryo development using digital holographic microscopy

“…We note that in previous work, Wacogne et al [20] measured the transmission spectra and used the lensing action of an oocyte to determine its refractive index. Importantly, this approach fails to provide spatial information on RI but instead reports a value for the whole sample, which may exclude developmentally important information.…”