Preserving In Vivo Tissue Complexity in a Mice Olfactory Nervous System Model Using Whole-Mount Analysis for Studying Neural Regeneration.

In the era of three-dimensional (3D) imaging, standard immunohistochemistry has been recognized as highly limited in studies of pathology and complex human anatomy. By analyzing only narrow slices, larger structures and essential aspects of tissue architecture may lose critical contextual details, leading to incomplete or misleading interpretations. While two-dimensional (2D) sections have supported a basic understanding of histoarchitecture, they are insufficient for capturing the true three-dimensional reality of biological tissues. Increasing numbers of studies across multiple anatomical regions now adopt techniques that isolate intact anatomical units - flat mount, whole-mount, or en face preparations - combined with high-resolution fluorescent microscopy. These approaches offer a more comprehensive visualization and interpretation of structural organization. This is particularly significant in the olfactory nervous system, where defining complex cellular mechanisms underlying its remarkable regenerative ability requires a full-thickness context. Thin sections risk missing key pathophysiological features that remain poorly defined. Given these limitations and the knowledge gap surrounding the cellular interactions driving olfactory regeneration, developing a refined whole-mount technique capable of preserving full-thickness tissue complexity was essential. Entire olfactory mucosae were isolated as full-thickness samples, accompanied by an optimized antibody-penetration protocol. High-resolution imaging (EVIDENT SpinSR) and 3D reconstruction enabled accurate visualization of cellular interactions in vivo.