Purpose of study. This study aims to establish the micro-structure of the vertebral endplate and its interface with the adjacent bone and disc in fresh, unstained tissue so that the structure can be related to normal and pathological function. Background. The endplate is key in both the mechanics, anchoring and nutrition of the disc. Understanding the detailed structure of the normal and pathological endplate is important for understanding how it achieves its functions. Advancements in imaging technology continually allow for greater understanding of biological structures. The development of two-photon fluorescence (TPF) combined with second harmonic generation (SHG), allows for the imaging of relatively thick, fresh samples without the need for staining. Methods. Bovine tail sections were sampled from the central region of the disc/vertebra interface. Samples were ground to provide a flat surface with a cross section including bone, endplate and disc. Samples were imaged using both TPF and SHG and images analysed using ImageJ. Results. The results detailed the interface between the bone, cartilage and disc. The SHG images show how the collagen fibre arrangement changes between the disc, endplate and subchondral bone. Due to its highly fluorescent nature, the interface between the calcified and non-calcified tissue was clear on TPF images. Conclusion. The application of TPF and SHG allowed us to image the endplate and its interfaces with the bone and disc in fine detail.
