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The epiphyseal plate, epiphysial plate, physis, or growth plate is a hyaline cartilage plate in the metaphysis at each end of a long bone.It is the part of a long bone where new bone growth takes place; that is, the whole bone is alive, with maintenance remodeling throughout its existing bone tissue, but the growth plate is the place where the long bone grows longer (adds length).
In zoology, a scale (Ancient Greek: λεπίς, romanized: lepís; Latin: squāma) is a small rigid plate that grows out of an animal's skin to provide protection. In lepidopterans ( butterflies and moths ), scales are plates on the surface of the insect wing , and provide coloration.
Epiphyseal growth plate: This transverse layer lies between the epiphysis and diaphysis. It’s composed of highly active chondrocytes and responsible for longitudinal bone growth. Consequently, the bone elongates at this growth plate until closure occurs at skeletal maturity.
Growth arrest lines, also known as Harris lines, are lines of increased bone density that represent the position of the growth plate at the time of insult to the organism and formed on long bones due to growth arrest. They are only visible by radiograph or in cross-section. The age at which the lines were formed can be estimated from a radiograph.
It contains the growth plate, the part of the bone that grows during childhood, and as it grows it ossifies near the diaphysis and the epiphyses. The metaphysis contains a diverse population of cells including mesenchymal stem cells , which give rise to bone and fat cells, as well as hematopoietic stem cells which give rise to a variety of ...
However, these transverse notches lack the typical cell columns found in normal growth plates, and do not contribute significantly to longitudinal bone growth. [12] Pseudo-epiphyses are found at the distal end of the first metacarpal bone in 80% of the normal population, and at the proximal end of the second metacarpal in 60%. [11]
Scutes on a crocodile. Reptile skin is covered with scutes or scales which, along with many other characteristics, distinguish reptiles from animals of other classes. They are made of alpha and beta-keratin and are formed from the epidermis (contrary to fish, in which the scales are formed from the dermis).
A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as well as possible hydrodynamic advantages.