Answer:
The correct answer is A. Intramembranous ossification forms the bones of the roof of the skull.
Explanation:
Intramembranous ossification is one of two types of bone formation and is responsible for the development of flat or laminated bones, especially those in the skull.
This type of ossification occurs within the connective tissue membranes, the so-called primary ossification center. Mesenchymal cells differentiate into osteoblasts. These, in turn, synthesize osteoids (newly synthesized bone matrix), which mineralize, giving rise to osteocytes. Several of these ossification centers happen simultaneously within a connective tissue membrane. Thus, the formed bone beams give a spongy aspect to the bone, allowing the penetration of blood vessels in these formed cavities, originating the bone marrow. The part of the connective membrane that does not ossify becomes the endosteum and periosteum, inwards and outwards.
While bone end-to-end ossification occurs from center to extremity, intramembranous bone develops differently from ossification nuclei, which expand and join over time. The skull, for example, ossifies in this way. For this reason, care should be taken when striking the head of newborns so as not to affect the brain that is not yet fully protected.
