These may have dozens of nuclei, and typically express major osteoclast proteins but have significant differences from cells in living bone because of the not-natural substrate. The size of the multinucleated assembled osteoclast allows it to focus the ion transport, protein secretory and vesicular transport capabilities of many macrophages on a localized area of bone. Location
In bone, osteoclasts are found in pits in the bone surface which are called resorption bays, or Howships lacunae. Osteoclasts are characterized by a cytoplasm with a homogeneous, "foamy" appearance. This appearance is due to a high concentration of vesicles and vacuoles. These vacuoles include lysosomes filled with acid phosphatase. This permits characterization of osteoclasts by their staining for high expression of tartrate resistant acid phosphatase (TRAP) and cathepsin K. Osteoclast rough endoplasmic reticulum is sparse, and the Golgi complex is extensive.At a site of active bone resorption, the osteoclast forms a specialized cell membrane, the "ruffled border", that opposes the surface of the bone tissue. This extensively folded or ruffled border facilitates bone removal by dramatically increasing the cell surface for secretion and uptake of the resorption compartment contents and is a morphologic characteristic of an osteoclast that is actively resorbing bone. Development
Since their discovery in 1873 there has been considerable debate about their origin. Three theories were dominant: from 1949 to 1970 the connective tissue origin was popular, which stated that osteoclasts and osteoblasts are of the same lineage, and osteoblasts fuse together to form osteoclasts.
Criteria
According to the Individuals with Disabilities Education Act an EBD classification is required if one or more of the following characteristics is excessively observed in a student over a significant amount of time:
Learning challenges that cannot be explained by intellectual, sensory, or health factors. Trouble keeping up or building satisfactory relationships with peers and teachers. Inappropriate behavior (against self or others) or emotions (shares the need to harm others or self, low self-worth) in normal conditions. An overall attitude of unhappiness or depression. A tendency to develop physical symptoms or fears related with individual or school issues.The term "EBD" includes students diagnosed with schizophrenia. However, it does not have any significant bearing on students who are socially maladjusted unless they also meet the above criteria. Criticisms
Providing or failing to provide an EBD classification to a student may be controversial, as the IDEA does not clarify which children would be considered "socially maladjusted". Students with a psychiatric diagnosis of conduct disorder are not guaranteed to receive additional educational services under an EBD classification. Students with an EBD classification who meet the diagnostic criteria for various disruptive behavior disorders, including attention-deficit hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), or conduct disorder (CD) do not have an automatic eligibility to receive an IEP or 504 Plan. Students considered "socially maladjusted", but ineligible for an EBD classification (i.e., students diagnosed with conduct disorder), often receive better educational services in special education classrooms or alternative schools with high structure, clear rules, and consistent consequences.