Intramembranous ossification is a process of bone formation that occurs directly within a connective tissue membrane. This method primarily forms flat bones, such as those in the skull and the clavicle. During this process, mesenchymal cells differentiate into osteoblasts, which then produce bone matrix, leading to the development of bone tissue. Unlike endochondral ossification, which involves a cartilage model, intramembranous ossification does not require a cartilage precursor. This allows for quicker bone formation, making it essential during the early stages of fetal development and for the healing of certain bone fractures.