Three-dimensional visualisation of human ovarian follicles using a whole-mount immunolabelling and optical tissue clearing method

In this study, we explored a new method for examining ovarian follicles - structures that contain the immature eggs - within human ovarian tissue. Traditional methods, which rely on two-dimensional imaging, can lead to mistakes in classifying the development of these follicles due to their spherical shape. To address this, we developed techniques to visualise the ovarian tissue in three dimensions. Using ovarian tissue from three patients, the tissue was processed using techniques called whole-mount immunolabelling (to detect structures) followed by optical clearing (to visualise the structures) and then analysed using microscopy. This enabled us to create detailed 3D images that showed the structures of the immature eggs and follicles across different planes of view. We discovered that conventional 2D assessments misclassified nearly 60% of the follicles, as certain developmental characteristics were only visible in the 3D images. This innovative approach marks the first time such detailed 3D imaging has been applied to human ovarian follicles. It not only enhances the accuracy of classifying follicle stages but also holds potential for improving fertility preservation techniques in the future. Overall, the study highlights the benefits of using modern imaging methods to gain better insights into ovarian health and development.