Confocal Raman microspectroscopy as an analytical tool to assess the mitochondrial status in human spermatozoa

Confocal Raman microspectroscopy was used to investigate human sperm cells. Raman mapping with a 532 nm excitation laser allowed to unambiguously characterize the nucleus, the neck, and, in particular, the mitochondria-rich middle piece of a human sperm cell. The effect of ultraviolet radiation on different organelles of the sperm was quantified by localized spectral Raman signatures obtained within milliseconds. Chemical changes within the sub-cellular structure of the sperm cells were recorded as a function of ultraviolet light exposure time, showing the proof-of-principle that Raman microspectroscopy can be a fast diagnostic method for detecting the mitochondrial and motility status of human spermatozoa.