Compressed vertebrae in Atlantic salmon Salmo salar: evidence for metaplastic chondrogenesis as a skeletogenic response late in ontogeny

Diseases of Aquatic Organisms

Laura Gil-Martens Brian K. Hall Ann Huysseune Alex Obach¹  P. Eckhard Witten¹ 

关键词: Notochord;    Skeletal deformities;    Vertebral malformations;    Metaplasia;    Bone;    salmon;    Chondrogenesis;   

DOI  :  10.3354/dao064237

学科分类：生物科学（综合）

来源: Inter-Research

【 摘 要 】

ABSTRACT: Anterior/posterior (a/p) compression of the vertebral column, referred to as ‘short tails’, is a recurring event in farmed Atlantic salmon. Like other skeletal deformities, the problem usually becomes evident in a late life phase, toolate for preventive measures, making it difficult to understand the aetiology of the disease. We use structural, radiological, histological, and mineral analyses to study ‘short tail’ adult salmon and to demonstrate that the study of adult fishcan provide important insights into earlier developmental processes. ‘Short tails’ display a/p compressed vertebrae throughout the spine, except for the first post-cranial vertebrae. The vertebral number is unaltered, but the intervertebralspace is reduced and the vertebrae are shorter. Compressed vertebrae are characterized by an unchanged central part, altered vertebral end plates (straight instead of funnel-shaped), an atypical inward bending of the vertebral edges, and structuralalterations in the intervertebral tissue. The spongiosa is unaffected. The growth zones of adjacent vertebrae fuse and blend towards the intervertebral space into chondrogenic tissue. This tissue produces different types of cartilage, replacing thenotochord. The correspondence in location of intervertebral cartilage and deformed vertebral end plates, and the clearly delimited, unaltered, central vertebral parts suggest that the a/p compression of vertebral bodies is a late developmental disorderthat may be related to a metaplastic shift of osteogenic tissue into chondrogenic tissue in the vertebral growth zone. Given the lack of evidence for infections, metabolic disorders and/or genetic disorders, we propose that an altered mechanical loadcould have caused the transformation of the bone growth zones and the concomitant replacement of the intervertebral (notochord) tissue by cartilaginous tissues in the ‘short tails’ studied here. This hypothesis is supported by the role thatnotochord cells are known to play in spine development and in maintaining the structure of the intervertebral disk.

【 授权许可】

Unknown