In intracytoplasmic sperm injection (ICSI), a single sperm is selected for direct injection into the ovum. This process poses an innate difficulty, as the natural sperm selection induced by the race to the ovum, perfected by millions of years of evolution, is replaced by a selection performed by a clinician. clinicians base the process of sperm selection on morphology and dynamics assessment, which is carried out using two-dimensional (2-D) imaging methods . These imaging methods lack quantitative contrast, because of the prohibition of using exogenous contrast agents in human ICSI, and have distinctive imaging artifacts.
A new acquisition method that enables the high-resolution, fine-detail full reconstruction of the three-dimensional movement and structure of individual human sperm cells swimming freely. Researchers achieve both retrievals of the three-dimensional refractive-index profile of the sperm head, revealing its fine internal organelles and time-varying orientation, and the detailed four-dimensional localization of the thin, highly-dynamic flagellum of the sperm cell. Live human sperm cells re-acquired during free swim using a high-speed off-axis holographic system that does not require any moving elements or cell staining.
The reconstruction is based solely on the natural movement of the sperm cell and a novel set of algorithms, enabling the detailed four-dimensional recovery. Using this refractive-index imaging approach, Researchers believe that they have detected an area in the cell that is attributed to the centriole. This method has great potential for both biological assays and clinical use of intact sperm cells.
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