The bodies of most teleost fish species are covered with specialized subepithelial structures known as scales. The scale is an epithelial appendage that differentiates from the dermal mesenchyme. Mammals, on the other hand, have no scales, but instead their bodies are covered with hair. Although their appearances are quite different, scales and hair can be considered structurally similar in that both of them are epithelial appendages distributed over the body surface in an orderly pattern. This analogy suggests that they may have the same evolutionary origin. But, to date, no molecular evidence has been presented that links scales and hair. A mutation at the rs-3 locus of medaka (Oryzias latipes) leads to almost complete loss of scales. We demonstrated that the rs-3 locus encodes ectodysplasin-A receptor (EDAR), which is required for the initiation of hair development in mammals. We identified a novel transposon inserted in the first intron of EDAR, which causes aberrant splicing. This work shows that EDAR is required for scale development in fish and suggests that it is an evolutionarily conserved molecule that is required for the development of epithelial appendages in vertebrates.

Object. Cervical spondylotic myelopathy (CSM) or myeloradiculopathy, frequent in adults with athetoid cerebral palsy, is a serious secondary disability in patients with an existing congenital handicap. Although several surgical procedures have been described for CSM in adults with athetoid cerebral palsy, none has had satisfying long-term results. The object of this study was to evaluate the effectiveness and safety of combined anterior—posterior fusion with wave-shaped rods and its influence on the stability of other spinal segments. Methods. Twenty-three patients with CSM and athetoid cerebral palsy underwent posterior fusion with wave-shaped rods combined with anterior interbody fusion with internal fixation; 20 patients, 17 men and three women, were followed for more than 5 years. This procedure yielded good results. The mean follow-up period was 8.7 years (range 5–17 years). At 1-year follow-up examination, ambulation had improved in 12 patients. Upper-extremity pain, deltoid muscle weakness, and ability to self-feed improved in almost all patients. Myelopathy recurred in one patient 8.5 years after surgery. The mean motion angle at the adjacent level to the fixed segment did not change postoperatively, but the mean motion between C-1 and C-2 increased and slight atlantoaxial subluxation occurred postoperatively in five patients. Conclusions. Combined anterior—posterior fusion can effectively improve neurological function in patients with CSM and athetoid cerebral palsy, even in those with severe involuntary movements. Postoperative rigid external fixation is not required.

In most multicellular organisms, homeostasis is contingent upon maintaining epithelial integrity. When unanticipated insults breach epithelial barriers, dormant programmes of tissue repair are immediately activated. However, many of the mechanisms that repair damaged epithelia remain poorly characterized. Here we describe a role for Plexin A (PlexA), a protein with particularly well-characterized roles in axonal pathfinding, in the healing of damaged epithelia in Drosophila. Semaphorins, which are PlexA ligands, also regulate tissue repair. We show that Drosophila PlexA has GAP activity for the Rap1 GTPase, which is known to regulate the stability of adherens junctions. Our observations suggest that the inhibition of Rap1 activity by PlexA in damaged Drosophila epithelia allows epithelial remodelling, thus facilitating wound repair. We also demonstrate a role for Plexin A1, a zebrafish orthologue of Drosophila PlexA, in epithelial repair in zebrafish tail fins. Thus, plexins function in epithelial wound healing in diverse taxa.

Anterior interbody fusion without decompression is an effective treatment for cervical OPLL myelopathy that resulted in stable long-lasting conditions.