In intramembranous ossification, what happens to trapped osteoblasts after osteoid is secreted and calcifies?

• A. They become osteocytes
• B. They remain osteoblasts
• C. They differentiate into chondrocytes
• D. They resorb bone

Answer: (A)

In intramembranous ossification, osteoblasts that secrete osteoid become embedded in the mineralizing matrix and turn into osteocytes. As the osteoid hardens, these osteoblasts get trapped in lacunae and differentiate into osteocytes, which remain inside the bone and extend processes through canaliculi to communicate and maintain the surrounding matrix. This process is why the correct choice is that trapped osteoblasts become osteocytes. The other possibilities don’t fit because cartilage-forming cells (chondrocytes) are part of endochondral ossification, not intramembranous, and bone resorption is carried out by osteoclasts, not osteoblasts.