Endocrine Abstracts

Histology has been a golden tool for biological research for decades. Nevertheless, whole organ histology is extremely time and resource consuming and most of the time impossible due to the distortions and lack of algorithms to correctly align thousands of sections. Light sheet-based microscopy is an important, innovative tool that offers nondestructive optical sectioning of selectively stained thick tissues at a spatial resolution between that of micro MRI and confocal microscopy and high-speed scanning capability. Recently developed tissue clearing methods coupled with laser-scanning microscopy made it possible to explore intact organs and to accurately acquire complete histological information about labeled cells/molecules in large tissues, including their spatial density and distribution. Among those techniques, the process called 3D imaging of solvent-cleared organs (3DISCO), has been proved to be a simple and inexpensive method for 3D analysis of immunolabelled transparent organs in embryonic and postnatal animals. Herein, combining 3DISCO with light-sheet laser-scanning ultramicroscopy, we studied the development and 3D organization of the hypothalamic-pituitary-gonadal axis in several mammalian species. Our 3D data demonstrate that with thorough biochemical optimization, we can now detect morphogenetic processes, cell migration and terminal differentiation during embryonic and postnatal development of mice. Moreover, this technique can be adapted to human tissues for volume imaging during fetal development as well as for the analysis of adult post-mortem tissues. The approach thus opens a novel route for high-resolution studies of brain architecture in mammals in physiological and pathological conditions.