The Effect of Light on Embryos and Embryo Culture

Abstract

In oviparous animals, the egg hatches outside of the body and is exposed to light; in some cases throughout the development of the fetus. In mammals, fertilization and the growth of embryos in vivo occurs in the dark but in human IVF, these embryos are exposed to variable light sources and intensities. Light can affect embryonic development in some species via either a direct toxic effect on the embryo, or indirectly via photo-oxidation of components in the media or oil. Although data regarding the effect of light on human embryos is lacking, it is prudent to take appropriate steps to minimize the potential harmful effects of both ambient and microscopic light on embryos. Disclaimer:The authors declare no conflicts of interest, whether of a financial or other nature J Reprod Stem Cell Biotechnol 3(2):46-54

How to Reduce the Potential Harmful Effects of Light on Blastocyst Development during IVF

“…The female reproductive system is able to protect oocytes, sperm cells, and embryos from potential environmental damage, for example, from visible and nonvisible light exposure. During the procedures of assisted reproduction, the gametes, zygotes, and the embryos are subjected to a variable spectrum of light from different sources, including: ambient light, illumination of the safety cabinet, or light emitted from the microscope or the time-lapse imaging cameras [1, 2].…”

“…Light exerts harmful effects on the physiology of mammalian gametes and zygotes [2, 3]. Previous studies have shown the damaging effect of visible light on oocytes, sperm cells, and embryos [4-7].…”

“…H 2 O 2 and its metabolites, hydroxyl radicals, can cause mitochondrial dysfunction and cellular damage [1]. Light may also affect cells via activating stress genes or even damaging DNA directly via ionization [2]. Light-induced photooxidation of culture media may also activate photooxidation of sperm and oocyte lipid membranes resulting in altered membrane structure, which could inhibit fertilization [2, 9].…”

Three-dimensional live imaging of bovine embryos by optical coherence tomography

“…However, stained embryos cannot be used for ET. The OCT system uses near-infrared light (λ: 900 nm), which has low cytotoxicity [24][25][26], and allows non-invasive observations of bovine embryo morphology; therefore, OCT-scanned embryos can be used for ET. We have also used the same OCT system to observe mouse embryos before ET and achieved a normal delivery after ET (Ohbayashi et al, unpublished data).…”

From Zygote to Blastocyst: Application of Ultrashort Lasers in the Field of Assisted Reproduction and Developmental Biology

“…When their difference, Ω = ω p − ω s , matches the vibrational frequency, resonant excitation, and in-phase vibration of all the molecules in the focal volume is observed. This boosts the Raman signal by several orders of magnitude, enabling the shortening of the acquisition time from seconds to milliseconds and minimize the light-toxic effects reported in [98]. The two most widely applied CRS techniques are stimulated Raman scattering (SRS) [99] and coherent anti-Stokes Raman scattering (CARS) [100].…”