2/29/2024 0 Comments Flat bones definitionSome of these cells will differentiate into capillaries, while others will become osteogenic cells and then osteoblasts. The process begins when mesenchymal cells in the embryonic skeleton gather together and begin to differentiate into specialized cells ( Figure 6.16 a). The flat bones of the face, most of the cranial bones, and the clavicles (collarbones) are formed via intramembranous ossification. Intramembranous Ossificationĭuring intramembranous ossification, compact and spongy bone develops directly from sheets of mesenchymal (undifferentiated) connective tissue. Some additional cartilage will be replaced throughout childhood, and some cartilage remains in the adult skeleton. By the time a fetus is born, most of the cartilage has been replaced with bone. Throughout fetal development and into childhood growth and development, bone forms on the cartilaginous matrix. This is why damaged cartilage does not repair itself as readily as most tissues do. All of these functions are carried on by diffusion through the matrix. Unlike most connective tissues, cartilage is avascular, meaning that it has no blood vessels supplying nutrients and removing metabolic wastes. As the matrix surrounds and isolates chondroblasts, they are called chondrocytes. This framework is a flexible, semi-solid matrix produced by chondroblasts and consists of hyaluronic acid, chondroitin sulfate, collagen fibers, and water. During fetal development, a framework is laid down that determines where bones will form. For skeletal development, the most common template is cartilage. Cartilage Templatesīone is a replacement tissue that is, it uses a model tissue on which to lay down its mineral matrix. There are two osteogenic pathways-intramembranous ossification and endochondral ossification-but bone is the same regardless of the pathway that produces it. By the sixth or seventh week of embryonic life, the actual process of bone development, ossification (osteogenesis), begins. In the early stages of embryonic development, the embryo’s skeleton consists of fibrous membranes and hyaline cartilage. Compare and contrast the processes of modeling and remodeling.Explain the growth activity at the epiphyseal plate.List the steps of endochondral ossification.List the steps of intramembranous ossification.By the end of this section, you will be able to:
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