Abstract
The cryoprotectant is commonly used to protect reproductive tissues during freezing and thawing. As an effort to investigate the osmotic behavior of cryoprotectant, near-infrared (NIR) techniques were applied to monitor the concentration of ethylene glycol (EG) within reproductive tissues. Spectroscopic analysis showed an absorption peak at 1460 nm for pure water, and the peak wavelength was increased by increasing EG concentration. Pure EG showed an absorption peak at 1586 nm. Based on this observation, a bandpass filter with a center wavelength of 1450 nm was selected to monitor EG concentration from NIR images by estimating water contents. The NIR image of pure EG showed an absorbance value as low as 2.419 due to high intensity at 1450 nm while that of pure water reached 2.902. A linear relationship was assumed between the absorbance value of image and EG concentration and was applied to the NIR images of mouse ovarian tissues soaked in 50% EG solution by weight. This procedure allowed the visualization of the concentration distribution of EG within reproductive tissues and also the analysis of osmotic behavior of EG according to time after soaking.
