RT Journal Article SR Electronic T1 Contrast-Enhanced Micro-CT Imaging of a Foetal Female Pelvic Floor Reveals Anatomical Details JF bioRxiv FD Cold Spring Harbor Laboratory SP 2024.11.10.622888 DO 10.1101/2024.11.10.622888 A1 Aaldijk, Dea A1 Halm, Sebastian A1 Liashchenko, Diana N. A1 Haberthür, David YR 2024 UL http://biorxiv.org/content/early/2024/11/11/2024.11.10.622888.abstract AB Background The pelvic floor is a highly important structure for the stability of the pelvis, providing support for the organs that lie within it. Until today, the detailed anatomy of the female perineal centre and the exact course of surrounding muscles remain controversial. This paper demonstrated a method to non-destructively obtain high-resolution contrast-enhanced x-ray microtomography images from a long-fixed sample and thereby aimed to contribute to the detailed anatomical knowledge about the female pelvic floor.Materials and Methods A human foetal pelvis of 20-21 weeks gestational age, formalin-fixed for 4 years, was immersed in Lugol solution and tomographically scanned periodically to document the staining process. The influence of the former fixation time was addressed by comparison with a short time fixed mouse pelvis. High-resolution imaging was performed by µCT, and the detailed analysis of the anatomy was supported by segmentation and 3D reconstruction.Results Lugol staining of long-fixed tissue worked well and showed no disadvantages compared to short-fixed tissue. Lugol staining and high-resolution µCT images provided a nicely stained image- stack with clearly identifiable tissue types. The anatomy of the foetal pelvis and its structures were resolved in detail. Interconnections between the external anal sphincter, the bulbospongiosus muscle and the superficial transverse perineal muscle could be shown within the perineal centre. There was no evidence for a skeletal muscle that corresponded to the formerly described deep transverse perineal muscle, instead there was cloudy-looking tissue, most likely smooth muscle fibres dispersed in connective tissue in a 3-D arrangement.Conclusions X-ray microtomography of Lugol-stained tissue is an excellent method to gain anatomical details in high resolution, in a non-invasive and non-destructive way, independently of the fixation time. Using this method, the topographical relationships of the pelvic floor muscles could be illustrated, showing their linkage within the perineal centre.Competing Interest StatementThe authors have declared no competing interest.