Question

Osteoclasts are the cells that degrade bone to initiate normal bone remodeling and mediate bone loss in pathologic conditions by increasing their resorptive activity. They are derived from precursors in the myeloid/ monocyte lineage that circulate in the blood after their formation in the bone marrow. These osteoclast precursors (OCPs) are attracted to sites on bone surfaces destined for resorption and fuse with one another to form the multinucleated cells that resorb calcified matrixes under the influence of osteoblastic cells in bone marrow.functions for OCPs and osteoclasts in and around bone other than bone resorption. For example, they regulate the differentiation of osteoblast precursors and the movement of hematopoietic stem cells from the bone marrow to the bloodstream; they participate in immune responses, and secrete cytokines that can affect their own functions and those of other cells in inflammatory and neoplastic processes affecting bone.

2)During intramembranous ossification, compact and spongy bone develops directly from sheets of mesenchymal (undifferentiated) connective tissue

The osteoblasts secrete osteoid, uncalcified matrix consisting of collagen precursors and other organic proteins, which calcifies (hardens) within a few days as mineral salts are deposited on it, thereby entrapping the osteoblasts within. Once entrapped, the osteoblasts become osteocytes . As osteoblasts transform into osteocytes, osteogenic cells in the surrounding connective tissue differentiate into new osteoblasts at the edges of the growing bone.

Several clusters of osteoid unite around the capillaries to form a trabecular matrix, while osteoblasts on the surface of the newly formed spongy bone become the cellular layer of the periosteum .The periosteum then secretes compact bone superficial to the spongy bone. The spongy bone crowds nearby blood vessels, which eventually condense into red bone marrow .The new bone is constantly also remodeling under the action of osteoclasts.

3)Intramembranous ossification begins in utero during fetal development and continues on into adolescence. At birth, the skull and clavicles are not fully ossified nor are the junctions between the skull bone (sutures) closed. This allows the skull and shoulders to deform during passage through the birth canal. The last bones to ossify via intramembranous ossification are the flat bones of the face, which reach their adult size at the end of the adolescent growth spurt.

Answer 1

The first points tells about the bone remodeling. Bone remodeling is the process by which the bones are replaced by new tissues, so that damaged cells are replaced like every other tissue. The matured cell is osteoclast it degrades and with the help of calcium, vit D etc the process is done. In this there are several steps which include new cell maturation bone resorption and invasion.

2) these are steps of intrembraneous ossification. Tbe osteoblast secrete some components which gets calcified and then surrounds the osteoblast.The osteoblast convert to osteocyte by this mechanism. The osteoclast stick to the spongy bones and form new periosteum. The bone remodeling also occurs between this.

3) here in this point we can see about intramembraneous ossification. It's the one of the essential process that takes place during fetal life to form rudimentary bones. Cartilage will not be present during this system. It's the one and only method by which the bones of head are formed. It is also considered as a process by which natural healing to the fractured bones.