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The scleral ring or sclerotic ring is a hardened ring of plates, often derived from bone, that is found in the eyes of many animals in several groups of vertebrates. Some species of mammals, amphibians, and crocodilians lack scleral rings. [1] The ring is in the fibrous outer layer of the eye, called the sclera.
Baló's concentric sclerosis is a disease in which the white matter of the brain appears damaged in concentric layers, leaving the axis cylinder intact. [1] It was described by József Mátyás Baló who initially named it "leuko-encephalitis periaxialis concentrica" from the previous definition, [2] and it is currently considered one of the borderline forms of multiple sclerosis.
Balo concentric sclerosis, an unusual presentation of plaques forming concentric circles, which can sometimes get better spontaneously. Schilder disease or diffuse myelinoclastic sclerosis: is a rare disease that presents clinically as a pseudotumoural demyelinating lesion; and is more common in children.
The N-D1 ring is larger (162 Å in diameter) than the D2 ring (113 Å) due to the laterally attached N-domains. The D1 and D2 domains are highly homologous in both sequence and structure, but they serve distinct functions. For example, the hexameric assembly of VCP only requires the D1 but not the D2 domain. [19]
Each osteon consists of concentric layers, or lamellae, of compact bone tissue that surround a central canal, the Haversian canal. The Haversian canal contains the bone's blood supplies. The boundary of an osteon is the cement line. Each Haversian canal is surrounded by varying number (5-20) of concentrically arranged lamellae of bone matrix.
The typical demyelinating plaques in Schilder's sclerosis are usually found bilaterally in the centrum semiovale. Both hemispheres are almost completely occupied by large, well defined lesions. Although plaques of this kind are largely prevalent in Schilder's sclerosis, smaller lesions can also be observed. [citation needed]
It is composed of 270 bones at the time of birth, [2] but later decreases to 206: 80 bones in the axial skeleton and 126 bones in the appendicular skeleton. 172 of 206 bones are part of a pair and the remaining 34 are unpaired. [3] Many small accessory bones, such as sesamoid bones, are not included in this.
Other diseases in this group are neuromyelitis optica (NMO), Balo concentric sclerosis, and Schilder's disease. [1] The graver course is one form of malignant multiple sclerosis, with patients reaching a significant level of disability in less than five years from their first symptoms, often in a matter of months. [2]