Categoría: Musculoskeletal System

SPINAL FRACTURE DUE TO ELECTRIC SHOCK

Musculoskeletal System
by Carlos Sandoval
Atlantic salmon, presmolt, FW, exposed to electric shock. Note the spinal fracture associated haemorrhage. The cause of the electric shock was an energized cable that fell into the tank.

Bone is a highly anisotropic, viscoelastic material that has the ability to continually adapt to changes in its physiological or mechanical environment. The capacity of bone to resist mechanical forces and fractures depends not only on the quantity of bone tissue but also on its quality. Bone is a composite material, made from a collagenous matrix and from minerals. The collagenous matrix provides toughness (fracture resistance) and the minerals increase the bone’s stiffness (bending resistance). By itself, the mineral phase is brittle and fractures easily....

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Heart and Skeletal Muscle Inflammation (HSMI) – Histopathology

Cardiovascular System, Musculoskeletal System
by Carlos Sandoval
Heart and Skeletal Muscle Inflammation (HSMI)

Heart and skeletal muscle inflammation (HSMI) is an emerging disease of marine-farmed Atlantic salmon (Salmo salar L), first recognized in 1999 in Norway, and later also reported in Scotland, Chile and Canada. HSMI is transmissible and, the weight of recent evidence supports the contention that the cause is an Orthoreovirus with the proposed name Piscine orthoreovirus (PRV). This virus has not yet been cultured in vitro, thereby hampering traditional experimental reproduction of the disease. As the name of the disease suggests, major changes in HSMI...

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Muscular Melanosis – Gross Pathology

Musculoskeletal System
by Carlos Sandoval
Muscular melanosis.

The term melanosis is used to describe the presence of unusual amounts of melanin in abnormal areas. Melanin is considered to plays a defensive role, since it is capable of absorbing and neutralizing free radicals, cations and potentially toxic compounds derived from the breakdown and phagocytosis of cellular material. Inflammatory reactions and tissue degeneration in bony fish frequently involve melanomacrophages. These macrophages contain fragments derived from phagocytized debris and cells, often erythrocytes, and pigments such as melanin, lipofuscin and haemosiderin. In salmonids these cytoplasmic granules...

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PRV – Atlantic salmon – IHC

Cardiovascular System, Musculoskeletal System
by Carlos Sandoval
Atlantic salmon, Piscine orthoreovirus in endothelial cells, Heart, IHC.

Piscine Orthoreovirus, is a segmented virus, non-enveloped RNA, 60 – 80 µm, with icosahedral shape, belonging to the family Reoviridae, subfamily Spinareovirinae and is the aetiological agent of Heart and Skeletal Muscle Inflammation (HSMI). The HSMI disease is diagnosed by the occurrence of histopathologic lesions in the heart and skeletal muscle; moderate to severe panmyocarditis (inflammation in the compact and spongy layers of the myocardium); and myocardial degeneration and necrosis. The skeletal muscle also shows moderate to severe myodegeneration and necrosis, especially of the red...

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Compression and Fusion of Vertebrate Bodies in Fish – Histopathology

Musculoskeletal System
by Carlos Sandoval
Vertebral compression. Masson's trichrome. Notochordal tissue is being replaced by chondrogenic tissue

Vertebral compression involves alterations of the growth plates, and is but one component of a range of changes with complex aetiology that result in spinal deformity. A striking feature of compressed salmon vertebrae is the coincidence of metaplastic synchondrosis and the shape alterations of the vertebral end plates, raising the possibility that either bone alterations induce the conversion of the notochord tissue or that changes of the notochord induce bone alterations. The current state of knowledge suggests the latter, since the notochord plays an important...

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