The formation of spongy bone involves a process called [ossification](https://). There are two types of ossification: intramembranous and endochondral. In intramembranous ossification, mesenchymal cells differentiate directly into osteoblasts, which lay down bone matrix to form trabeculae. In endochondral ossification, a cartilage model is first formed and then gradually replaced by bone tissue. Osteoclasts and osteoblasts work together to remodel and maintain the trabecular structure.
