Eventually, all of the cells within the nidus develop into, and display the morphologic characteristics of, an osteoprogenitor cell. Once a nidus has been formed the MSCs within it stop replicating.Īt this point, morphological changes in the MSCs begin to occur: The cell body is now larger and rounder the long, thin cell processes are no longer present and the amount of Golgi apparatus and rough endoplasmic reticulum increases. The process of intramembranous ossification starts when a small group of adjacent MSCs begin to replicate and form a small, dense cluster of cells that is called a nidus.
Light micrograph of a nidus consisting of osteoprogenitor cells that are displaying a prominent Golgi apparatus. Furthermore, the mesenchymal stem cells are widely dispersed within an extracellular matrix that is devoid of every type of collagen, except for a few reticular fibrils. Before it begins to develop, the morphological characteristics of a MSC are: A small cell body with a few cell processes that are long and thin a large, round nucleus with a prominent nucleolus that is surrounded by finely dispersed chromatin particles, giving the nucleus a clear appearance and a small amount of Golgi apparatus, rough endoplasmic reticulum, mitochondria, and polyribosomes. A mesenchymal stem cell, or MSC, is an unspecialized cell that can develop into an osteoblast. Mesenchymal stem cells within mesenchyme or the medullary cavity of a bone fracture initiate the process of intramembranous ossification. Unlike endochondral ossification, which is the other process by which bone tissue is created during fetal development, cartilage is not present during intramembranous ossification. Transmission electron micrograph of a mesenchymal stem cell that is displaying typical ultrastructural characteristics. Intramembranous ossification is also an essential process during the natural healing of bone fractures and the rudimentary formation of bones of the head. Intramembranous ossification is one of the two essential processes during fetal development of the gnathostome (excluding chondrichthyans such as sharks) skeletal system by which rudimentary bone tissue is created.
Mesenchymal bone development that forms the non-long bones
0 kommentar(er)
