Tissue samples and histological analysis
We used six hand specimens obtained from six fresh-frozen cadavers, who provided informed consent to use their organs and tissues for scientific purposes (McHanwell et al., 2008; Riederer et al., 2012). The specimens had no previously documented hand injuries or surgeries. All specimens were thawed at room temperature and dissected in the Human Anatomy Department of the School of Medicine of the University of Granada (Spain). Specifically, the carpal bones were dissected, and the scaphoid and lunate bones joined by the SLIL were carefully extracted and transferred to the Laboratory of Histology of the Medical School of the University of Granada. Then, the SLIL were carefully separated from the carpal bones and fixed in 10% buffered formalin (Panreac Química S.L.U., Barcelona, Spain) for histological analysis. As controls, several structures were also dissected and extracted from the same human hands, including samples of the flexor tendon (FT), carpal ligament (CL), articular cartilage (AC), triangular fibrocartilage (TF) carpal articular capsule (CC) and retinaculum (RT). These tissues were fixed and processed using the same protocols used for the SLIL. Authorization was obtained from the Department of Anatomy of the Medical School of the University of Granada, which approved the study.
Formalin-fixed SLIL and control tissues were dehydrated, cleared in xylene and embedded in paraffin following routine histological methods. 5 µm-thick sections were obtained from each sample, dewaxed in ethanol series, rehydrated and stained with hematoxylin and eosin (HE) (Panreac Química S.L.U.) using standard protocols. Histological images were then obtained using a Pannoramic Desk DW II histological scanner (3DHISTECH, Budapest, Hungary) from controls and from 6 zones of the human SLIL (Figure 1): dorsal region -part 1- (D1), dorsal region -part 2- (D2), membranous region -part 1- (M1), membranous region -part 2- (M2), palmar region -part 1- (P1) and palmar region -part 2- (P2).